366 DISCOVERY REPORTS 



THE MALE GENITAL SYSTEM 



EXTERNAL 



Since the testes are abdominal the only part of the generative system which is visible 

 externally in the adult is the smooth tapering penis (Plate II, fig. i), which is normally 

 withdrawn into a slit-like pouch in the ventral abdominal wall. In mature Fin whales the 

 penis varies in length from 2-o to 2-5 m. (Mackintosh and Wheeler, 1929, p. 380), 

 while in immature whales it is usually nearer i-om. When the penis is completely 

 withdrawn only the genital slit can be seen. The slit lies in front of the anus, the distance 

 between the centres of the two openings being equal to about 6-7 per cent of the total 

 length of the body (Mackintosh and Wheeler, 1929, p. 324). The deep genital slit is 

 usually accompanied by a set of short converging grooves. Two of these, the most 

 pronounced, lie immediately behind the slit (Plate II, fig. 1) and converge towards a 

 point on the mid-ventral line of the body about half-way between the anus and the genital 

 slit. Two others flank the slit and converge anteriorly. A raphe, more distinctly seen in 

 the foetus, runs from the posterior side of the root of the penis along the skin in the 

 middle line to the anus. 



It is a character common to all Cetacea that in the adult and in later foetal life the 

 penis is, except in the erected condition, withdrawn into such a pouch with swollen lips 

 on the ventral surface of the abdomen. In the stallion also the penis is withdrawn into 

 a very similar pouch of skin. There seems to be some confusion in the literature with 

 regard to the correct term for this slit and for the various parts of the penis. The penis 

 is smooth and tapering, with a conical terminal portion, occupying about one-third of 

 its length, at the apex of which the urethra opens. Around the base of the cone there 

 is a slightly raised fold of integument. The confusion in the terminology seems to have 

 arisen from the fact that the various authors have described the penis in different states 

 of contraction and to the doubt which exists whether the conical terminal part is a true 

 glans or not. Eschricht (1849, P- 81) held the conical terminal portion to be a true glans, 

 and therefore considered the ring-like fold of skin at the base equivalent to a praeputium. 

 Beauregard and Boulart (1882, pp. 169-75), who did not consider the terminal portion 

 to be a true glans, speak of the genital slit as " a sort of praeputial sac ". In one of the two 

 Phocaena embryos and a Beluga embryo described by Daudt (1898, pp. 243-5) the 

 genital slit was not yet developed and the penis was apparently free on the abdominal 

 wall. This author appears to apply the term " preputium" to the whole of the sheath of 

 skin surrounding the penis as far as the base of the terminal cone. He placed the same 

 interpretation upon the structures observed in Balaenoptera (p. 289). Daudt wrote 

 "the point of involution (Umschlagstelle) of the pseudopraeputium " — that is the ring 

 of skin around the terminal cone — "is recognizable in a fully everted penis as a slight 

 ring-like protuberance. If the shaft is inverted the pseudopraeputium disappears but is 

 represented by the whole penis sac". [The "penis sac — Penistasche" — was Weber's term 

 (1904, p. 260) for the genital slit.] 



In this paper it is proposed to adopt Eschricht's interpretation and to call the ring-like 



