and at each pole of the elongated sac, by the subcircular villous patch. The umbilical cord, f, formed by one venous and two arterial trunks, and by the slender neck of the allantois, g, with the connecting cellular tissue and the covering of amnios, is short and somewhat flattened. It measured about 6 inches in length, before the division of the vascular trunk, and about 3 inches in circumference. The inner surface of the amnios is roughened by brownish hemispherical granules, from I line to th of a line in size, commonly about half a line; the outer surface is finely wrinkled, but smooth. The bag formed by the mucous or unvascular layer of the allantois is of considerable size, is continued from the base of the umbilical cord, so expanding between the chorion and amnios as to prevent any part of the amnios attaining the inner surface of the placenta. The allantois divides, where the amnios begins to be reflected upon it, into three sacculi: one extends over the inner surface of the annular placenta, and a little way into one end of the chorion: a second extends into the opposite end of the chorion, a'; it there bends round toward the placenta, and its apex adheres at that part to the first division of the allantois: the third prolongation subdivides into two smaller cavities, each terminating in a cul-de-sac, encompassing, and closely attached to, the primary divisions of the umbilical vessels. The line of adhesion of the amnios to the allantois, where it is reflected upon these cul-de-sacs, measures 3 feet 6 inches.

The primary branches of the umbilical arteries and vein diverge from the umbilical cord in four divisions: they reach, first, the borders of the placenta, and then ramify in its substance and upon the inner surface of the chorion, being supported there, and more or less surrounded, by the layer of the allantois called 'endochorion.' Upon the endochorionic vessels are developed a number of flattened, oval, or subcircular bodies, e, e, of a compact, structureless tissue, varying in diameter from an inch or more to half a line. On separating the chorion from the allantois, these bodies were found to belong entirely to the latter membrane: the vessels upon which they seem to be developed pass on their chorionic side, the bodies adhering to the allantoic side of the sheath of the vessel they are most abundant near the placenta, and become wider apart as they approach the poles of the chorion: 1 counted 120: the smaller ones occur on the free duplicatures of the allantois continued from the umbilical trunks: in almost every case they are developed on the course of the large vessels, and are restricted, with few exceptions, to that part of the allantois which is in contact with the chorion. Their free surface is

smooth and polished, not villous like the cotyledons of the Ruminantia; from which they likewise differ in projecting inward toward the cavity of the allantois, like the so-called cotyledons of the sloth: they are not mere precipitates of inspissated matters of the allantoic fluid, like the hippomanes' of the Mare.

A male and female Indian Elephant paired December 18, 1863, and at other times up to January 8, 1864, when they were kept apart. For twelve months there was no conspicuous increase of the abdomen: after that period it was obvious to close inspection, on the left side: then the mammary glands enlarged, with slight occasional oozing of milk; and on August 3, 1865, the young was born; it stood 2 feet 10 inches high, and weighed 175 lbs. Thus the period of gestation, reckoned from the date of first coitus, is 593 days.

The Hyrax has an annular placenta more subdivided than in the Elephant. The venous blood returns from it at three places, the centres of as many divisions of the belt, which, however, are continuous by thinner portions of placental substance. The villi are imbedded in decidual substance, and the surface of its attachment to that remaining on the uterus is less limited than in the Elephant. The placental zone seems relatively tighter, the ends of the chorion swelling out more, than in Carnivora. The perissodactyle number of ribs-twenty-two pairs, the simple stomach and complex cæcal structures, the hoofs of the unsymmetrically tetradactyle fore-foot and tridactyle hind-foot, as in a larger extinct hornless rhinoceros, the close repetition of dental characters in the diminutive existing species, not merely as to pattern of grinding surface of molars, but of kinds and manner of growth of all the teeth, the incisors being developed as in Rhinoceros incisivus, demonstrate the low taxonomic value of the placental character, according to which the Hyrax, as well as the Elephant, would be classed with the Carnivora.

§ 404. Development of Carnivora.-In the foetal Cat, about the middle of the period of gestation, the chorion, fig. 578, a, a, is a curved arc 6 inches in long diam., by 2 inches in short diam., with obtuse ends; it is girt in the middle by an annular placenta, b, 14 inch broad: the zone is concave transversely within, of a mingled grey and red colour when uninjected: the chorion on each side of the placenta is slightly folded, and of a reddish colour. The foetal surface of the placenta is lobulated:

1 He must have counted much upon the ignorance of his auditors or readers who could affirm that the HYRAX hangs by Rhinoceros mainly by the pattern of its molar teeth.' CCLXX". p 111.

the maternal placenta or serotine decidua is present, and can be separated as a distinct layer. The mucous layer of the allantois expands from the uterine extremity of the umbilical cord upon the vascular layer (chorion or exochorion), forming broad duplicatures about the allantoic vessels outside; the trunks

of these are in the free margins of the folds, and at the opposite margins the folds of the non-vascular layer of allantois recede and spread over the vascular layer or chorion, to which they cohere. The vitellicle, d, extends into the pointed horns, f, f, between amnion and placenta, at right angles to the latter: it is attached by a slender pedicle, g, to a loop of small intestine: it usually contains a yellowish liquid, with some small loose fimbriate precipitates. In the amniotic liquid crumbs of meconium occur toward the end of gestation. The navel-string is very short. The Cat is in heat, for about ten days, before she is a year old; and is prolific to the ninth year: bringing forth at least twice a year in the wild state, and three or four times in domesticity. The

'xx. vol. v. p. 141, no. 3565.

gestation is fifty-five or fifty-six days; and she brings forth usually from four to six young.

In the Lioness the exterior of the placenta is marked by anfractuosities like those of the brain; the inner surface is divided into small irregular convex lobes by deep sulci. In the zonular placenta of the Dog the maternal portion cannot be defined and separated as in the Cat: the uterine surface to which the placenta adheres presents a finely reticulate substance, the meshes being formed by orifices of apparently utricular glands, aggregated in the interspaces of larger alveoli, scattered over the surface with intervals of between half a line and two lines. When the fœtus has attained a length of five or six inches, this alveolar decidua has acquired a thickness which makes it recognisable as the maternal portion of the placenta. The period of gestation of the Wolf, Jackal, and Dog is 63 days.

579

A modification of the annular placenta, analogous to that in the Elephant, obtains in some Carnivores, e. g. the Weasel tribe (fig. 579, Putorius Furo); two portions of a subcircular form, A, B, appear as a double placenta, but they are united by a much thinner tract, C, also receiving ramifications of the allantoic vessels. The umbilical cord, one-third of an inch in length, goes to one of the cotyledons, whence the vessels extend to the other. The omphalo-mesenteric duct expands into a pyriform vitellicle, five lines in length. The Ferret produces from five to eight young; she has usually eight teats; has a six-weeks' gestation, and produces twice a year. In the Martens the placenta is undivi

ded (Mustela martes, M. foina, &c.); the decidua serotina sinks into its substance along a narrow tract at the middle of the outer surface of the zone, as in the Elephant: they bring forth, commonly, twice a year, but are less prolific than the Weasels. The navel-string is very short: the allantois is more elongated; a trace of vitellicle may be seen in a small bilobed yellowish patch, upon the inner surface of the placenta, where the navelstring ends.

In the Hyæna the deciduous substance becomes fused with the chorionic placental processes: it is moderately thick, spongy,

tomatose, non-coherent: the fœtal processes penetrate cavities in the decidua apparently homologous with the utriculi of the human uterine lining, and having as little the structure of true follicular glands. The original deciduous capsule of the ovum is reduced to a very thin layer of mucous substance, exterior to the placental zone.

Seals have rarely more than two young, and more commonly but one, at a birth. In the latter case the foetus and its membranes are limited to one horn of the uterus, not extending into the opposite horn, as in Cetacea. The placenta is zonular, in four or five continuous or connected divisions. In Phoca vitulina the diameter of the zone parallel with the long axis of the ovum is between two and three inches. In parturition the sclerous tissue of the symphysis pubis becomes relaxed, allowing divarication of that part of the pelvic arch, which, consistently with the reduced hind limbs, is smaller than in land Carnivores.

The gestation of the Bear (U. americanus) is seven months: the young, usually two in number, are born as well shaped as in other Carnivora, but are more naked: the eyelids are closed, and so continue for about four weeks. From some information I have received respecting the Badger, it would seem, like the Roe, to have a long gestation in proportion to its size. The young, as with the Bear, are blind at birth.

§ 405. Development of Quadrumana.—The Makis (Lemur) have sometimes one, commonly two, rarely three young at a birth. A pair of the Lemur albifrons, captive at the Jardin des Plantes, Paris, copulated December 23, and afterwards repeatedly for five or six days: the female brought forth April 13, after a gestation of fifteen weeks. The new-born young was covered with very short hairs, and had its eyes open.'

The Marmosets (Hapale Jacchus) resemble Lemur in the number of young: the gestation is three months: the young is naked at birth, except upon the head, and gets clothed in three or four weeks. In Callithrix sciureus the long twisted umbilical cord is chiefly in connection with a circular thick discoid placenta: but some of the branches of both the two arteries and two veins extend (as it seemed to Schroeder von der Kolk) to a smaller and thinner circular villous tract, like a second placenta at the opposite end of the chorionic sac.

The Howler (Mycetes seniculus) has a single placenta, also circular, discoid, from which the foetal blood is returned by two 'CCLXXVII". p. 50.

2 Ib. p. 55, pl. 6, fig. 1. Rudolphi found the placenta single in Hapale Jacchus.