122 Proceedings of the Royal Physical Society. 



many arrested developmental conditions, which suggest the 

 evolution of the Cetacean from an animal provided with a 

 visible scrotum. The course followed by the vas deferens is 

 much more indicative of historical or reversionary conditions 

 than of progressive evolution, since it does not by any means 

 pursue the shortest course from the testis to the base of the 

 prostate. As regards the testis itself, it is clear that it 

 has moved from its original position on the dorsal wall of the 

 abdomen to a point on the opposite or ventral aspect of the 

 abdominal cavity, rotating on its long axis as it travelled 

 along a portion of its possible path of " descent " towards a 

 scrotum. The existence of the fibrous gubernaculum above 

 described, not only provides a satisfactory reason for the posi- 

 tion in which the testis of the adult porpoise is found, but, 

 from the association of this fibrous band with the ventral 

 aponeurosis and the anterior end of the innominate bone, we 

 may obtain some interesting light in connection with the 

 descent of the testis in the case of an animal possessing a 

 scrotum. If the gubernaculum of the porpoise had been 

 attached a short distance farther back, the testis might 

 readily have been drawn from under cover of the hinder 

 border of the ventral muscles, and thus, along with a con- 

 tinuation of the rotation of the testis, the condition and 

 position of the testis within a scrotum would have been 

 completely and exactly reproduced. That is to say, the 

 testis would have again placed itself on the dorso-mesial 

 aspect of that digital prolongation of the peritoneum which 

 has been above described in relation to the loop formed by 

 the vas deferens, and thus the testis would have reproduced 

 the relation to the bursa testis (tunica vaginalis testis) of 

 animals possessing a scrotum. 



Although the porpoise does not possess a scrotum, the dis- 

 section seems to us to warrant the statement that it possesses 

 an inguinal region in which the peritoneum forms an in- 

 fundibular prolongation external to the pelvic bones, and in 

 the direction of a scrotum had such existed. In fact, this 

 peritoneal funnel is not unlike that which persists in the 

 case of human congenital scrotal hernia. 



The Prostate Gland was an organ of considerable size. 



