in a rudimentary condition, it will be interesting to know that among some of the earlier mammals the pineal gland may have assumed functional importance as an eye. Prof. Henry F. Osborn 85 shows that in the skull of the curious mammal Tritylodon, of Owen, there is seen a parietal foramen in exactly the same position and relation as in the lizard Sphenodon.

Professor Osborn regards this fact of remarkable interest, as it adds greatly to the rapidly accumulating evidence for the reptilian affinities of the mammalia. Professor Owen, in the description of this unaccountable opening, suggested that it might be due to posthumous injury.

Professor Marsh,86 in a description of the skull of Diplodocus, a Dinosaur, describes a fontanelle in the parietal on the median line directly over the cerebral cavity. He adds, however, that this may be merely an individual variation.

Professor Cope 87 observes an enormous fronto-parietal foramen in the skull of Empedocles molaris, a curious creature from the Permian.

It would appear evident from these facts that at one time the pineal gland, which in the mammals is in a rudimentary condition and in certain Lacertilia sufficiently perfect, as an eye, to be sensitive to light impressions at least, was, in certain extinct mammals and reptiles, of large size and functionally active. It is a significant fact that no sooner does some one opposed to evolution undertake to lay down the law by setting a boundary to type features, than a discovery is made that breaks down the barrier. Thus Dr. Thomas Dwight, 88 in an interesting memoir on the "Significance of Bone Structure" in which he makes a brave defence for teleology, says, in speaking of the persistence of the vertebrate plan, “There are never, for instance, more than two eyes or one mouth or two pairs of limbs," and, lo! an extra eye is immediately added.

Dr. Spencer Trotter 89 has made a study of the collar bone and its significance, in which he accounts for its presence or absence in mammalia by correlating it with the life habits of the animal in the use of the fore limb. He says "Every fully developed tissue in an organism is needed or it would not be there; and just so soon as by increasing change in life and habits it becomes a factor of less and less importance to the animal, it fails more and more to attain its former standard of development, and in time

falls back to the primitive condition from which it arose and finally disappears."

Many new and interesting facts have been added sustaining the affinity between the birds and reptiles. Prof. O. C. Marsh 90 made a careful study of the Archeopteryx in the British Museum. The new points he has added bring out still more strongly the extraordinary characters blended in this creature. Among other features he discovered the separate condition of the pelvic bones, and shows that while it must be considered a bird, yet it has true teeth, bi-concave vertebræ, three separate fingers in each hand, all furnished with claws, metatarsals and metacarpals, equally unanchylosed and the pelvic bones separate, as already mentioned.

Dr. J. Amory Jeffries,91 in a study of the claws and spurs on birds' wings, has presented an interesting table showing the number of phalanges in each finger, from the highest to the lowest family of birds, with the presence or absence of claws recorded for each finger. This table shows very clearly that the higher birds have fewer phalanges and no claws, and as one approaches the lower families the phalanges increase in number, the first finger having two phalanges and the second and third fingers being tipped with claws.

In a brief study of the tarsus of low aquatic birds,92 made with special reference to the interpretation of the ascending process of the astragalus with the intermedium of reptiles, I observed a separate centre of ossification for this so-called process, observed its unquestionable position between the tibiale and fibulare, its increase in size with the growth of the bird and its final anchylosis with the proximal tarsal bones. In the bones of a young Dinornis, which through the courtesy of Dr. Henry Woodward I was kindly permitted to examine in the British Museum, the ascending process was large and conspicuous and firmly anchylosed with the coossified tarsals to the distal end of the tibia. Professor Marsh,93

in a study of the metatarsal bones of Ceratosaurus, a Dinosaur discovered by him, found that the metatarsals coössified in the same manner as those of the Penguin.

The question as to the existence of a sternum in Dinosaurian reptiles has long been in doubt. Professor Marsh 94 has, however, discovered in Brontosaurus, one of the largest known Dinosaurs, two flat bones which he regards as clearly belonging to the sternum. They correspond to the immature stage of similar parts in birds.

Dr. Alexander Agassiz, 95 in a study of the young stages of certain osseous fishes, shows that while the tail is a modified heterocercal one, it is for all that in complete accordance with embryonic growth and paleontological development; and, independently, Dr. John A. Ryder 96 finds that "the median fins of fishes normally present five well-marked conditions of structure which correspond inexactly to as many stages of development, which, in typical fishes, succeed each other in the order of time."

Mr. James K. Thatcher 96" in a study of the "Median and Paired Fins, a contribution to the history of vertebrate limbs" shows "that the limbs with their girdles were derived from a series of similar simple parallel rays, and that they were a specialization of the continuous lateral folds or fins evidenced in embryos, which were with some probability homologous with the lateral folds or metapleura of the adult Amphioxus."

A great amount of work has been done in making clear the earlier stages in the development of animals and breaking down the hard and fast lines which were formerly supposed to exist between the larger divisions. Dr. C. S. Minot,97 in a series of papers on Comparative Embryology, in referring to the work accomplished says "These researches have completely altered the whole science of comparative anatomy and animal morphology by entirely upsetting a large part of Cuvier's classification and the idea of types upon which it was based, substituting the demonstration of the fundamental identity of plan and structure throughout the animal kingdom from the sponges to man."

Prof. C. O. Whitman,98 in describing a "rare form of the blastoderm of the chick, in which the primitive groove extended to the very margin of the blastoderm, terminating here in the marginal notch first observed by Pander," justly contends that "in the origin of the embryo from a germ-ring by the coalescence of the two halves along the axial lines of the future animal, and, secondly, in the metameric division which followed in the wake of the concrescence," we have evidence of the annelidan origin of the vertebrates since concrescence of the germ bands is a well established fact for both chatopods and leeches.

The tracing of apparently widely divergent structures to a common origin has engaged the attention of many of our investigators. Not only has a large amount of evidence been offered to show a common origin of widely separated structures, but memoirs of a

speculative and theoretical character have given us a possible clew to the avenues we may follow in further establishing a proof of the unity of origin of forms and parts.

Dr. Francis Dercum 99 gives an interesting review of the structure of the sensory organs and urges that the evidence goes to prove the common genesis of these organs.

Prof. A. Hyatt 100 has presented an interesting study of the larval history of the origin of tissue. He attempts to show a phyletic connection between the Protozoa and Metazoa, and also to show that the tissue cells of the latter are similar to asexual larvæ "and are related by their modes of development to the Protozoa just as larval forms among the Metazoa themselves are related to the ancestral adults of the different groups to which they belong." Dr. John A. Ryder 101 has studied the law of nuclear displacement and its significance in embryology. In a discussion of this subject he says "The mode of evolution of the yelk is of great interest, and doubtless occurred through the working of natural selection. It is evidently adaptive in character, and the necessity for its presence as an appendage of the egg grew out of the exigencies of the struggle for existence."

Mr. H. W. Conn, 102 in a paper entitled "Evolution of the Decapod Zone" gives a number of striking and suggestive facts explaining the reason of the multiform and diverse character of the larvæ of decapod crustaceans. He shows in what way natural selection has affected the young. What has seemed an almost insoluble mystery, as to why the early stages of closely allied crustaceans. should be so often diverse in their varied armature of long spines, their powers of rapid flight, etc., are explained on the ground of natural selection. In another memoir by the same author,103 on the significance of the "Larval skin of Decapods," a very complete discussion of the views of authors are given. At the outset he shows that the crustaceans are a particularly favorable group for the study of phylogeny and then suggests the character of the ancestral form of the Crustacea from the significance of the larval envelope. The author infers from his studies that "all Decapods are to be referred back to a form similar to the Protozoa (Zox) in which the segments of the thorax and probably of the abdomen were present, and whose antennæ were locomotive organs."

Not the slightest justice can be done this admirable discussion in the brief reference here made, but the perusal of it will certainly

impress one with the profound change which has taken place in the method of treating a subject of this nature compared to the treatment it might have received in pre-Darwinian days. Indeed the features discussed in this paper would not have attracted a moment's attention from the older naturalists.

Since Darwin published his provisional theory of Pangenesis it has provoked speculative efforts on the part of some of our naturalists to devise other hypotheses which might answer some of the objections urged against Darwin's hypothesis. Space will permit only a mention of a few of these papers. Prof. W. K. Brooks104 presented, in brief abstract at the Buffalo meeting eleven years ago, a provisional theory of Pangenesis. These views more elaborated are now published in book form under the title of "The Laws of Heredity." An illustrious reviewer says it is the most important contribution on the speculative side of Darwinism that has ever appeared in this country. He has also aptly termed studies of this nature molecular biology. Dr. Louis Elsberg at the same meeting also read a paper on the plastidule hypothesis.

Dr. John A. Ryder 105 has made an interesting contribution entitled "The Gemmule versus the Plastidule as the Ultimate Physical Unit of Living Matter." In this paper he discusses Darwin's provisional theory of Pangenesis and shows it to be untenable from Galton's experiments.

Haeckel's provisional hypothesis of the Perigenesis of the Plastidule is clearly stated, and he closes by saying that the logical consequences of the acceptance of Haeckel's theory and with it the theory of dynamical differentiation-because the latter is no longer an hypothesis-forever relegate teleological doctrines to the category of extinct ideas.

The widespread public interest in Darwinism arose from the fact that every theory and every fact advanced in proof of the derivative origin of species applied with equal force to the origin of man as one of the species. The public interest has been continually excited, by the consistent energy with which the church, Catholic and Protestant alike, has inveighed against the dangerous teachings of Darwin. Judging by centuries of experience, as attested by unimpeachable historical records, it is safe enough for an intelligent man, even if he knows nothing about the facts, to accept promptly as truth any generalization of science which the church declares to be false, and conversely to repudiate with equal