394 DISCOVERY REPORTS 



height and forms a sort of lip for it, which, running round the lateral faces, loses itself 

 behind in the labia minora ". There is frequently a number of fleshy tags around the base 

 of the clitoris in the adult, and the development of the fleshy pad between the urinary and 

 genital openings has already been mentioned. The sides of the genital opening are also 

 thrown into abundant radiating rugae. All these fleshy protuberances would appear to 

 have the function of retaining a firm grip on the smooth cylindrical penis during copulation. 



Mackintosh and Wheeler (1929, pp. 381-2) described the structure known as the 

 "vaginal band", which is frequently found in all species of Balaenoptera yet examined 

 but is especially frequently seen in B. phy solus. This structure stretches across the 

 genital opening from the anterior fleshy pad to the posterior wall of the opening. As 

 the " vaginal band " is an important and remarkable feature of the anatomy of the genital 

 system a brief account of the structure will be given here. The "vaginal band " is a thick 

 strand 7-8 cm. long and not less than 1 -o cm. in diameter in the adult. It stretches, as 

 already mentioned, from the anterior fleshy pad in front of the genital opening to the 

 posterior lip. In mature whales one end only of this band is usually found as a tag — the 

 "vaginal tag " — 5-6 cm. long, attached usually anteriorly, sometimes posteriorly. " The 

 band is composed mainly of fibrous connective tissue with a few small blood vessels. 

 Many minute convoluted ducts course through the tissue.... Transverse sections show 

 that the character of the band is not similar throughout. That part — about one-third — 

 which faces the opening of the vagina is covered with papillae. At each side the papillae 

 give place to a typical epidermis which covers the remaining two-thirds of the surface 

 and resembles the epidermis covering the blubber. Sections give the impression that 

 the outer surface epidermis has grown in round a solid strand of the underlying tissue 

 but has not completely covered the inner surface" (Mackintosh and Wheeler, p. 381). 



The complete vaginal band is not usually found in mature whales, since the act of 

 coition cannot well take place without rupturing it. Only one instance is recorded in 

 which coition had certainly taken place without rupture of the band. In this instance 

 the whale was pregnant, but the vaginal band, though complete, did not stretch com- 

 pletely across the genital aperture since one end was attached somewhat at the side of it. 



Thus the opening of the vagina in early life is closed by a hymen-like structure which 



is ruptured at coition. The occurrence of this structure is too frequent to allow the 



"vaginal band" to be looked upon as an abnormality, but in the opinion of the present 



author, it may be regarded as comparable with the hymen which stretches longitudinally 



across the vaginal opening of the mare. As already mentioned, the mole (Owen, 1868, 



vol. in, p. 688) has at first only a urinary aperture behind the clitoris and the genital 



aperture appears later by the rupture of the skin between the urinary opening and the 



anus. 



THE MAMMARY GLANDS 



The mammary glands are inguinal in position, one on each side of the vulva, the 

 nipples lying in the mammary grooves as has already been described. According to 

 Ryder (1885, p. 135) the nipples present the condition termed "pseudo-nipples" by 

 Gegenbaur. The walls of the nipple fossa are raised up as a rim enclosing a cup-like pit 



