2G8 DELPHINID^. 



This genus is easily known from Delph'mus by the lowness of the 

 forehead, the short and depressed form of the beak, the posterior 

 position of the dorsal fin, the body being attenuated behind, and by 

 the breadth and flat, expanded form of the nose of the skull. 



The OS hyoides of L. leucoplewus is large and broad. 



ia. Beak elongate. Rostnim of skull lotif/er than the length of the brain- 

 case. Teeth-line some distance from the notch. Electra. 



b. Beak ynoderate, Bostrum of skull only as long as the brain-case. Teeth 

 not quite to the notch. 



C. Beak verg short. Bostrum of skull onlg as long as the brain-case. Teeth 

 nearly to the notcli. 



a. Bostrum of skull longer than the length of the brain-case. Teeth-line 

 some distance from the notch. Electra. 



1. Lagenorhynchus Electra. The Electra. 

 Skull rather depressed; nose flattened above, expanded and re- 

 flexed on the side behind, rather shelving in front, sides rather 

 contracted in the middle, rather longer than the head, and once and 

 three-quarters the length of the width at the notch ; intermaxillary 

 broad, flattened, nearly two-thirds of the width, with a large, wide 

 groove for the greater part of its length ; triangle flat, rather con- 

 cave behind, with a lozenge-shaped, rather raised, rugose space in 

 the front half; teeth f-j, rather small, cylindi-ical, conical, slightly 

 curved, acute, four in an inch ; the lower jaw regularly converging, 

 straight on the sides in front, rather swollen behind, and shortly 

 obliquely truncated in 'front, the gonyx rather produced. 



Lagenorhynchus Electra, Gray, Zool. Erebus Sj Terror, 35. 1. 13 (skuU); 

 Cat. Cetac. B. M. 1850, 100. 



Inhab. ? 



a. Skull ? Purchased. The specimen figured in the ' Voyage 



of the Erebus and Terror.' 



SkuU : length, entire, 17| inches ; of head, 8^ ; of nose, 9| ; of 

 teeth-line, 7 ; of lower jaw, 14| ; width of temple, 1Q\ inches ; at 

 notch, bh ; at middle of beak, 4 ; of intermaxillarj^, 2|. 



This skull is very like the former, but it is considerably larger, the 

 nose is longer in proportion, and the head is much more depressed 

 in the middle and spread out at the sides. 



2. Lagenorhynchus caeruleo-albus. 



Teeth j^ ; white, back bluish, with oblique streaks on the sides, 

 belly white. 



Delphinus cferuleo-albus, Mvi/cn, Act. Nat. Cur. xvi. 609. t. 43. f. 2 ; 



Gray, Zool. E. <^'- T. 42 ; Bcichcnb. Cetac. Anut. t. 19 (skull^). 

 Lagenorhynchus cfBruleo-albus, Grai/, Cat. Cetac. B. M. 1850, 100; 



Cassin, U. S. Expl. Exped. 31. t. 6.'f. 2. 

 Uelphinus albirostratus, I'ecde, Zool. Expl. Exped. Mamm. 38, ed.l, 1848, 



Inhab. East coast of South America, llio de la Plata. 

 Length 5 feet G inches. Skeleton in Anat. Mus. Berlin. 



