1883.] PROF. FLOWER ON THE DELPHlNIDiE. 505 



vertebne distinct, or with irregular unions towards the middle of the 

 series. Manus small, short and broad ; second and third digits 

 nearly equal, fourth slightly shorter. No dorsal fin. 

 One species, M. monoceros, Linn. Arctic seas. 



Delphinapterus, Lacepede, Hist. Nat. des Cetaces, Tabl. des 

 Ordres &c. p. xli (1804) '. 



Beluga, Gray, Spicilegia Zoologica, p. 2 (1828). 



Agrees with the last in all the characters above mentioned except the 

 dentition. Teeth \ to f^, of moderate size, occupying the anterior 

 three-fourths of the rostrum only and corresponding portion of the 

 mandible, separated by intervals considerably wider than their own 

 diameter, and implanted obliquely, the crowns inclining forwards, 

 especially in the upper jaw. 



D. leucas (Pallas), the Beluga or ^Vhite Whale of the Arctic seas, 

 is the only well-established species. It has been divided into several 

 (rhinodon, declivis, and angustatus) by Cope, but these require con- 

 firmation. A skull of a young animal in the British Museum, not 

 distinguishable from the northern form, but said to be from the 

 coast of New Holland, was described in 1827 by Dr. Gray, under the 

 name of B. hinyii. No further light has since been thrown upon this 

 habitat. 



b. Atlas and axis firmly united. 

 Phoc^na, Cuvier, Eegne Animal, i. p. 279 (1817). 

 a. Crowns of teeth laterally compressed. 



Teeth p, small, occupying nearly the whole length of the rostrum, 

 with compressed spade-shaped crowns, separated from the root by a 

 constricted neck. Rostrum of skull rather shorter than the cranium 

 proper, broad at the base and tapering towards the apex. Pre- 

 maxillse raised into tuberosities in front of the nares. The frontal 

 bones forming a somewhat square elevated protuberance in the middle 

 line of the skull behind the nares, rising altogether above the flattened 

 nasals (see fig. 2, p. 471). Pterygoids very small and widely separated 

 in the middle line. Symphysis of mandible very short. Vertebrae : 

 C. 7, D. 13, L. 14, C. 30 ; total 64. First to sixth cervical vertebrae, 

 and sometimes the seventh also, coalesced. Manus of moderate size, 

 oval, slightly falcate ; second and third digits nearly equal in length, 

 fourth and fifth well developed but shorter. Dorsal fin near the 

 middle of the back, triangular ; its height considerably less than the 

 length of the base ; its anterior edge frequently furnished with one 

 or more rows of conical horny tubercles. 



Phoccena communis, F. Cuvier. Hab. European and American 

 coasts of North Atlantic. A closely similar if not identical species 



1 The Beluga being the first mentioned and type of this genus, in fact the 

 only species of those now recognized by cetologists known to Lacepkle, should 

 remain as its representative, although by Gray and others it has been removed 

 to a neve genus, and the name Belphinapterun transferred to species unknowu to 

 its founder. 



