PKODELPIIINUS LONGIROSTRIS. 75 



PRODELPIIIXL'S LONGIROSTRIS (Gray). 



DKl2)hi)u(s lougirostiifi. Gray, Spic. ZooL, 182-3, p. 1. 

 DclphiuKS microps. Gray, Zool. Ere. & Terr., 184(3, p. 42, i)1.25. 

 Dclphiiias alopc, Gray, Cat. Oct. Brit. Miis., 1850, p. 118. 

 Dtlphiuiis stt'iwrhijnchus, Gray, Cat. Seals aud Whales, 18oG, p. 39G. 



This S])ecies is distingiiisbable from those of the same genus, which 

 we have already cousidered, by the small size of the cranium as com- 

 pared with the beak. In the Characters and Divisions^ Professor Flower 

 places the four names given in the foregoing synonymy in one of his 

 sections of Cli/menia. In the List he unites stenorht/nchus with hmgi- 

 rostris, and holds alope and microps as distinct species. Of the lattei-, 

 however, he remarks that it is "probably the same as the next [P. 

 longirosfris).'^ 



To the union of stcnorhynclms and longirostris I subscribe with little 

 hesitation. Furthermore, the specific identity of sfenorhynvhiis and 

 microps does not appear to me very doubtful. The tyi)e of microps is, 

 however, somewhat smaller than the typeofs<e?ior%/jt7/».9, though both 

 skulls seem to be of the same age. The interinaxllla^ are a little nar- 

 lowed in front of the "triangle" in the former species but not in the 

 latter. The beak is relatively longest and narrowest in sfenorhynclnis. 

 On the other hand, in the remaining proportions the two skulls are ahke, 

 and the teeth are equally numerous and similar in form; the pterygoid 

 bones are alike in form, having flat sides and a very sharp keel. The 

 difference in the proportional width of the intermaxilhe at the middle 

 of the beak is due to the partial absorption of these bones in P. sfcno- 

 rhynchus. 



The coronoid process of the mandible is strongly developed in both 

 skulls. The roots of the teeth in P. stenorhynchus are flattened, a little 

 thickened, and imperforate. 



If Delpliinus alopc is to be kept separate it must be because of its rela- 

 tively broader beak aud keeled mandibular symphysis. There is, how- 

 ever, in the collection of the National Museum, a skull. No. 21108, which 

 is intermediate in form between alopc aud longirostris, and binds these 

 two species together. The beak is broader than in longirostris or 

 microps but narrower than in alopc, and the symphysis niandibuli is more 

 strongly keeled than in the two former species, but less than in alopc. 

 Tiie skull is nearly as large as that of stenorhynchus (see table of meas- 

 urements, page 76). 



The specimens described by Dr. Liitken in his recent work,* under 

 the name of ^^Prodelphinus alope,''^ are certainly not the Belphinus alopc 

 of Gray { = P. longirostris Gray). On the other Imnd, the skeleton de- 

 scribed as "P. longirostris (Schl.) "does, I believe, belong to the species 

 under consideration. 



* Liitken, K. Danskc Vidcusk. Selsk., Skr., C.th Rackke, v, pt. 1, IHS'.t, pp. 43-47. 



