GENUS PIIOC.ENA. 117 



4» 



12. PHOCENA Ciivier. 



Phocmia, Cavier, R&gne Auiiual, i, 1817, p. 279. 



Tlie genus Phoccena is readily distinguishable from all the remaining 

 genera of the family, except NeomcriSj by the shape of the teeth. From 

 the hitter genus it differs in having a dorsal fin. 



Professor Flower's admirable diagnosis holds good for all the species, 

 except, as I have already pointed out elsewhere,* for one observed in 

 the North Pacific by Mr. Dall, which 1 have named P. BaUii. In this 

 species the number of vertebriv rises to ninety-seven or ninety-eight, 

 and the dorsal fin is falcate. In these characters the species shows 

 affinity to Lagenorhynchus, but, on the other hand, the skull (the only 

 portion of the skeleton preserved) is that of a Fhocana. 



Putting aside the number of vertebrai and the form of the dorsal fin, 

 we still have in the form of the teeth, the shape and position of the 

 pterygoids, the form of the premaxilhe, and the presence of a dorsal fin, 

 sutticient characters for the differentiation of the genus. 



I have elsewhere stated my opinion that the number of valid existing 

 species of this genus is probably reducible to four, viz, Fhocwna com- 

 munis Lesson; Phoc(ena lineata Cope; rhocama spinij^innisVimmcii^Un'; 

 PJiocwna dallii True. P. ijectoralis Peale, I have shown in another 

 l)artof tliis work to be jn-obably identical with Lagcnorhynclms clcctra 

 Gray (p. 101). P. tuberculifer a, Gray, was finally admitted by that au- 

 thor to be the same as P. communis Lesson. P. hrachycion. Cope, and 

 P. vomeri)ia, Gill, have never been proven identical with P. communis, 

 Lesson, but Professor Flower, in 1883, expressed the opinion that such 

 was probably the truth, and 1 have myself reached that conclusion. As 

 regards the identity of P. lineata, however, the material at command is 

 scarcely sufficient to warrant any very positive assertions. The type- 

 skeleton is missing and nothing but the painted cast remains, and it is 

 evident that to base any conclusions upon the color of a painted cast 

 alone is hazardous. Special difficulty attends the discrimination of 

 species in this genus, because both the body as a whole and the skeleton 

 are subject to great variations in proportions and details of form. 



The characters drawn from the relation of the vomer to the palatines, 

 which are employed by Professor Cope and Dr. Gill in the separation of 

 the different nominal species, are valueless, t To find other characters 

 is a task to which I have devoted my attention, but thus far without 

 success. I am constrained for the present to look upon P. communis, 

 hrachycion, lineata, and vomerina as identical. 



The species here recognized are, thevefore, Phocama communis Lesson, 

 1827; Phoccenas pinipinnis Burmeister, 1SG5; Phocwna dallii True, 1885. 



* Proc. U. S. Nat. Mus., viil, 1885, pp. 95-98. 



t Cope, Proc. Acad. Nat. Sci. Philadelphia, 187G, p. 134. Gill, 1. c, 1HG5, p. 178. I 

 should state, however, that Dr. Gill has iuformed me that he no louger places any 

 confidence in these chai'acters. 



