PRODELPIIINUS FKCENATUS. 71 



Neveitlieloss, since the skulls and external i)ro[)ortions of the s[)eci- 

 meus identified by Dr. Liitken as P. doris, attennatns, and (dope are 

 almost identical, the question uaturally arises whether the difference 

 in number of vertebme may not possibl^^ be due to individual variation. 



It would be very interesting in this connection to know the vertebral 

 formula of Gray's P.pnnciatus^ the skull of which seems to me identical 

 with the type-skull of P. attcnnatus, but whose style of marking resem- 

 bles Dr. Liitken's P. dons, No. 4. Since Dr. Liitken states that the 

 types of Gray's I>. moorci and J), walkeri ( = 7>. dclphis), which are la- 

 beled "Walker's No. 1" and "Walker's No. 2," were really obtained by 

 Captain Andrea, it occurs to nie that the type of I), punctatus, which 

 is labeled "Walker's No. 3," may also have been obtained by Captain 

 Andrea. It is from a point near the Cape Verde Islands, only a few 

 miles distant from the place in which Dr. Liitken's P. doris. No. 2, was 

 derived, and was probably caught in the same year. 



The specimen which Dr. Liitken places under "P. obscurus (Gray)"* 

 certainly does not belong to that species, which is, I believe, a Lagen- 

 orliynchus. In color this specimen seems to me intermediate between 

 the two specimens figured on page ol.t In external proportions it agrees 

 with P. doris No. 4,| and in skeletal proportions with this and other 

 specimens on pages 32-33. 



In conclusion, it may be said that it is necessary for the present to 

 regard P. attenuatus as a distinct species, on account of its different 

 vertebral formula. 



The difference in color between P. frocnatus and Dr. Liitken's speci- 

 men of P. doris nniy be regarded as due to difference in age. As al- 

 ready stated, however, if it should be shown hereafter that the number 

 of vertebne is subject to variation, there is apparently no other reason 

 why all the specimens should not be regarded as belonging in one vari, 

 able species. 



*ajj. cit., p. 42. tOi). cit. lOp. cit., p. 31. 



