Cinosternidæ, but not more so perhaps than that of some of the aged Chelydridæ.
The generative organs of both sexes possess many points of interest, and many striking peculiarities of structure. The oviducts of the female are greatly extended, and each possesses a distinct sphincter near its prominent orifice. Moreover, the distal or in- ferior third is abruptly narrowed into a small duct — the analogue, perhaps, of the Fallopian ducts of higher Vertebrates; but the remainder corresponds in relative position and value to the uteri of of Marsupials and Monotremes. The lining membranes of these organs is remarkably white and smooth, and with the exception of perhaps two or three minute and isolated mucous glands presents neither crypt nor follicle— nothing apparently to provide for the covering of the eggs of the reptile; yet it would seem, in spite of appearances to the contrary, that this mucous lining must never- theless possess the power of rapidly secreting calcareous material.
The ovaries proper average from three to five inches in length, and appear merely as the thickened edge of the mesenteric membrane with which they are invested, and which suspends them in proper position and connects them with the kidneys and other viscera. They are scarcely more dense than those of the Ranidæ, and the ova are produced only in a narrow strip of the outer part of the meso-ovarium.
The male organ is usually represented by comparative anatomists as large, both in structure and in form, and resembling closely what obtains in the Struthionidæ, particularly the male Struthio camelus. The singular intricacy of the structure, while it presents an analogy to some of the Marsupials, as the Echidnæ and Mono- tremes, in which the same organ is likewise quadrifid, more nearly resembles the double bifurcated organ of the Crotalidæ and Viperinæ, yet is even more complicated than in these reptiles. This hardly tallies with Professor Owen's supposition that the bifid ex-tremity of the male organ is an adaptive structure corresponding to the bilateral or double uterus of females, and having reference to multiparous reproduction. If such were the case, we should reajsonably expect to find the female Aspidonectes possessed of a quadruple uterus ; whereas, as already shown, it is but a double organ. The cloacal orifice, which is located half an inch or more from the extremity of the somewhat elongated tail, would seem to suggest an explanation of the length of the latter organ, which
