SUMMARY 443 



Weber (1886), however, while deriving the Cetacea from some very primitive pro- 

 ungulate source says (p. 240): "Ich halte es fur ganz unrichtig die Cetaceen entweder 

 von Carnivoren oder von Ungulaten abzuleiten. Meine Meinung geht dahin dass sie 

 einem generalisirten Saugethiertypus in Mesozoischen Zeitalter entstammen der 

 zwischen Carnivora und Ungulata mitten inne steht". 



With regard to the lobulation of the kidney, all authors, notably Daudt (1898) and 

 Anthony (1926), who have discussed its significance, agree that it is related to the 

 necessity for an increase in the excreting surface of the kidney in correlation with (a) 

 the great volume of a whale in comparison with its surface and (b) the greater amount of 

 excretion carried out by the Cetacean kidney in comparison with that of other mammals. 

 Daudt, in the latter connection, points out that a whale's diet has an exceptionally high 

 water content, whether it be crustaceans or fish (rorquals) or cuttle-fish (sperm whales), 

 and further that quantities of sea water are probably engulfed with the food, the salts of 

 which will tend to promote the excretion of urine. This author also remarks that the 

 skin is entirely devoid of sweat glands, so that the excreting function of the skin is 

 probably taken over by the kidneys. Anthony draws an analogy between the increase in 

 the excreting surface of the kidney of the Cetacea brought about by lobulation and the 

 increase in the number of cellules in the neo-pallial cortex brought about by gyren- 

 cephaly in the higher mammals. 



Quite evidently, at any rate, the lobulation has a purely physiological significance. It 

 is found also in the otter, where it is probably an adaptation to aquatic life, the bear and 

 the elephant, where it is probably correlated with the surface-volume ratio. It is also 

 found in seals where again it is probably an adaptation to aquatic life. 



SUMMARY 



Some description of the male genital system of the Fin whale {Balaenoptera physahis) 

 has been given from the dissection of two foetuses 2-65 and 1-23 m. in length respec- 

 tively. 



The main points in the anatomy of the genital system are the following: 



1 . The smooth conical penis is retractile into a ventral pouch by means of a pair of 

 retractor penis muscles. 



2. The penis is surrounded proximally by a muscular sheath derived from the 

 panniculus carnosus. 



3. The penis contains a single aseptate corpus cavernosum forming a crus at the base 

 of the penis. It is accompanied by a single corpus spongiosum, which forms no crus and 

 no bulb. The corpora cavernosa and spongiosa continue together into the terminal cone, 

 which is therefore not a true glans. 



4. The crus corporis cavernosi is embraced by an ischio-cavernosus muscle (erector 

 penis) whose attachments to the ischiac portions of the pelvic bones are small. The 

 interpelvic ligament of Struthers exists, but is small and poorly developed in the Fin 

 whale. The triangular ligament of Struthers was found. 



