EXTERNAL FEATURES 



Presumably the ancestors of the Cetacea were hairy, as seems clearly 

 indicated by the fact that in the fetal state bristles are more numerous 

 about the head than in adults, but the hair of the body has long since 

 disappeared. Adult mysticetes may have a few bristles about the head 

 as well as scattered cutaneous pits, evidently constituting the relics of 

 hair follicles. These are most noticeable, at least in Balaenoptera, be- 

 neath the chin tip, where they are gathered in a sharply defined cluster, 

 which often shows to good advantage in a photograph. In fetuses there 

 may be a row of widely spaced bristles along the rostrum, and scat- 

 tered at other points upon the head. Among the odontocetes, Stenodel- 

 phis is the only one that retains a few bristles in adult life, while Mono- 

 don and Delphinapterus (the white whale or beluga) never have them 

 at any stage in their development. In Tursiops, at least, among the por- 

 poises there are scattered pits about the lips which may have follicular 

 affinity. 



The specialization in this direction has progressed farther than in the 

 loss of hair, however. The Cetacea have lost sudoriferous glands and 

 possibly the sebaceous as well, although authors seem to be at variance 

 on the latter point. For instance Beddard (1900) stated that the seba- 

 ceous glands have begun to vanish. Certainly they are absent from most 

 sections of the skin that have been examined, but perhaps they still 

 persist in certain circumscribed areas. 



In a section of the skin of Tursiops before me, prepared by G. B. 

 Wislocki, the corneum is tissue thin, and associated with it seem to be 

 even thinner elements of a stratum lucidum. Next comes an excessively 

 thickened stratum germinativum of very homogeneous character. The 

 papillae of the corium are unusually slender and long (for their thick- 

 ness), while the coreum insensibly merges with the tela subcutanae 

 the true blubber layer. In reality the blubber layer should probably 

 be considered as a definite component of the coreum, for it is very 

 tough and fibrous, whether relatively collapsed (in an emaciated ani- 

 mal), or gorged with fat cells, and totally different from the simple layer 

 of soft, subcutaneous fat of the seals. 



In some ways the whole layer of skin and blubber is remarkably 

 tender. In a freshly caught Balaenoptera the corneum is relatively even 

 thinner and more tender than in a porpoise, and may be rubbed off in 

 great patches by the palm of one's hand, the resulting sheet resembling 

 tissue paper. I have easily scored the surface with a finger nail, and af- 

 ter inserting a pocket knife for the full length of the blade, one may cut 

 as easily as through so much cheese. One would suppose that the first 



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