388 DISCOVERY REPORTS 



course forward through the vagino-peritoneal canal and then bends round towards the 

 middle line on to the neck of the bladder. In Delphinus delphis (Fig. 7 B), where the 

 testis has the renal position, Anthony found an S-shaped bend shortly below the testis, 

 which he identified with the convoluted portion of the vas deferens of Mesoplodon. 

 From Mesoplodon, through Delphinus delphis, may be derived the condition found in 

 Balaenoptera, which has been inserted for comparison into the figure (Fig. 7 C) given 

 by Anthony for Mesoplodon and Delphinus. 



With regard to this, however, Weber (1898, p. 60) says: "From knowledge of the 

 relations in the Monotremes and various Insectivores we know that the windings of the 

 vasa deferentia prove nothing in this respect". 



The existence of a cremaster sac in Mesoplodon must be taken as undoubted evidence 

 that some such sac, in which the testis was lodged, must have existed in the Cetacean 

 ancestor ; but, in the opinion of the present author, there is no evidence that full descent 

 took place, although the present ventral position of the Cetacean testis is certainly not 

 its primitive one so that partial descent at least must have occurred. Attention is 

 drawn, however, to the extremely primitive arrangement of the testicular attachments. 

 In the Cetacea, as in the Mammals listed by Weber as showing true testicondy, the 

 testis with the epididymis is enclosed in a reduplicature of the peritoneum, attached to 

 the dorsum of the neck of the bladder and forming a plica diaphragmatica laterally. The 

 genital glands, as has already been remarked, are suspended in the most primitive 

 mammalian way, and the method of suspension is almost identical in both sexes. This 

 constitutes, in the opinion of the present author, one of the most important features of 

 the male Cetacean genital system. It indicates a very early origin of the group possibly 

 from some forerunner in which the testis, as in the ox embryo of 22-5 cm. mentioned 

 by Weber (1898, p. 56), lay outside a small cremaster sac. In the ox embryo the testis 

 lies at first within the abdominal cavity outside the inguinal ring before descending into 

 the cremaster sac, and it is suspended in the Cetacean manner. In the adult complete 

 descent into a scrotum takes place. 



The vascular supply 



The vascular supply in the genital region of Balaenoptera musculus has been described 

 in some detail by Bouvier (1889, p. 103), and also by Beauregard and Boulart, who paid 

 special attention to the vessels supplying the testis and epididymis. Murie (1873) also 

 described the genital blood supply in Globicephala. 



In the present investigation the blood vessels were not injected and thus the course 

 of the major vessels only can be described. In actual fact there is such an inextricable 

 network of small vessels in this region that only the broadest outlines of their disposition 

 could be given in any account. 



Rapp (1837) considered that the iliac arteries do not exist in the Cetacea. Daudt, 

 however, calls the two lateral postcaval trunks, which join to a common postcava in 

 the region of the kidney, the venae iliacae. The arteries actually identifiable with the 

 common iliacs are very short and come off from the dorsal aorta, right and left, 



