584 ZOOLOGY 



SKCT. 



majority of Mammals through a canal — the inrpiinal canal — in tlie 

 posterior part of the abdominal wall to lie in the j?eri9ia.'w?n, or 

 space between the urinogenital and anal apertures, or to be 

 received into a pendulous pouch of skin, sometimes double — the 

 scrotum. The ^M'Hi's, present in the males of all Mammalia, con- 

 sists of two mriiora cavernosa, firm strands of vascular tissue 

 attached proximally to the ischia except in the Monotremes, 

 Marsupials and some 3^]dentata, and a central strand, the corpus 

 sponfjiosnni, perforated by the urethral canal and often dilated at 

 the extremity to form the glans. The two vasa dcferentia, con- 

 tinued from the epididymcs, which are in close relation to the 

 testes, join the urethral canal near the neck of the bladder, each 

 often having connected with it, near its distal end, a sacculated 

 reservoir — the vcsicula scminalis. A small diverticulum of the 

 proximal part of the urethra — the uterus mascAdimis — may be a 

 remnant of the Miillerian duct. Surrounding this part of the 

 urethra is a glandular mass — the prostate gJand; and the ducts 

 of a pair of small glands — Cowper's glands — open into the urethra 

 near the base of the penis. 



The ovaries are compressed, oval bodies which retain their 

 primary position in the abdomen, or pass backwards into its 

 posterior or pelvic part. In the Monotremes, large Graafian 

 follicles project on the surface of the ovary, while in other Mammals 

 the Graafian follicles are very small, and the surface of the ovary 

 almost smooth. 



The oviducts have dilated funnel-like abdominal openings, the 

 edges of which, except in the Monotremes, are fimbriated or 

 fringed. In the Monotremes the two oviducts are distinct through- 

 out their length, and open separately into a urinogenital sinus. 

 In nearly all the Theria more or less coalescence takes place. In 

 the Marsupials this coalescence is confined to the anterior part of 

 the vagina. In the Opossums (Fig. 1211, A) the two oviducts 

 are merely in close apposition at one point behind the uteri, 

 and there is no actual coalescence. In the rest of the Marsu- 

 pials (B, C) the anterior portions of the oviduct in the region 

 {vagina) behind the uteri unite to form a median chamber 

 which may send backwards a median diverticulum {median 

 vagina, Vg. B), and in this way communicate behind with the 

 urinogenital passage. In the Eutheria there is a single median 

 vagina (Fig. 1212, Vg.) formed by the union of the posterior parts 

 of the two oviducts. In some cases the two uteri (A, ui,) remain 

 distinct; in others their posterior portions coalesce (B,C), the 

 anterior parts remaining separate, so that there is formed a median 

 corpus uteri with two horns or vornua. In Primates and some 

 Edentates the coalescence goes still further, there being an un- 

 divided uterus (D) in addition to an undivided vagina, the only 

 parts of the oviducts which remain distinct from one another being 



