PARTS AND FEATURES 



ever, there are practically no details of this system so far known that are 

 surely attributable to an aquatic life. It is usually stated that the ceta- 

 cean kidney is lobulated, but this is a misleading term. That of most if 

 not all large terrestrial mammals is lobulated, but in the Cetacea it takes 

 a different form, each kidney appearing to be an aggregation of a mul- 

 titude of small kidneys closely packed and contained within a single 

 envelope. The significance of this condition is unknown. 



Although of doubtful significance aquatically, there are many inter- 

 esting features of the gonads of highly adapted aquatic mammals, some 

 of which may here be accorded brief mention. Engle (1926) has re- 

 ported on some of the equipment of the males as follows: 



Bulbo-urethral 

 Seminal vesicles Prostate gland 



Odobenus none present none 



Eumetopias none present none 



Phoca none present none 



Halicore 1 pair one none 



Phocaena none paired none 



Dephinapterus . . none present none 



Sibbaldus none present none 



As previously mentioned there is a tendency coupled with the aquatic 

 life to eliminate the scrotum together with other bodily protuberances. 

 Accordingly, among Pinnipedia, Sirenia, and Cetacea, the Otariidae and 

 Odobenidae are the only ones which retain this feature. In the Cetacea 

 the testes are not truly abdominal, but are situated in "a pouch near the 

 inguinal ring." As Meek (1918) has stated, in the porpoise the penis 

 is greatly modified, the copulatory part being differentiated from the 

 rest and separated by a joint which allows a wide range of movement. 

 This jointed character is not present, or at least apparent, in Mysticeti. 

 The cavernous body of the penis proper is single in the Cetacea and 

 double in Sirenia. In both sexes of the Cetacea the uro-genital and anal 

 orifices are situated within a common sulcus bordered by a pair of labia. 



RESPIRATORY SYSTEM 



The respiratory system and its appurtenances is perhaps the most criti- 

 cal factor in the cetacean equipment, for every activity of an aquatic 

 mammal is governed by the necessity of renewing as often as necessary 

 the supply of air. This need is often antagonistic to many of its other 

 activities, as it very seldom is in the case of a terrestrial mammal. 



During his investigations of the lungs of the porpoise Tursiops, G. 



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