273 CETACEA 
one-fourth the length of the ramus; other cranial characters as in 
the preceding genus. Teeth 31 to 34, of comparatively large size 
(5-6 mm. in diameter); surface of their crowns finely grooved. 
Vertebre: C7, D12, L15, C32; total 66. Represented by 
S. rostratus, from which the forms which have received other names 
are probably not specifically separable. 
Sotalia.—Pterygoids narrow, not meeting in the middle line, 
and in their inner borders diverging posteriorly, instead of being 
parallel as in the preceding genera; other cranial characters much 
as in Steno. Teeth tolerably large (4-5 mm. in diameter), 3% to 35, 
with smooth enamelled surface. Vertebre: C7, D12, L 10-14, 
22; total 51-55. Pectoral fin broad at base, the breadth being 
caused by the considerable development and position of the two 
outer digits. Six species are provisionally recognised as distinct, 
including the Chinese White Dolphin (8. sinensis) and 8. pallidus 
from the river Amazon. 
Bibliography of Cetacea—D. ¥. Eschricht, Untersuchungen iiber die Nordischen 
Wallthierc, 1849, contains a copious bibliography of the group up to the date of 
publication. Since that time numerous monographs on special families and 
genera have been published, and a large illustrated general work, Ostéographie des 
Cétacés, by P. J. Van Beneden and P. Gervais, 1869-80. Besides those already 
referred to in the footnotes, the following may be mentioned ; viz. J. F. Brandt, 
“Untersuchungen itber die Fossilen und Subfossilen Cetaceen Europa’s,” in 
Mém. de UV Acad. Imp, de St. Pétersbourg, 7®me sér. vol. xx. 1873 ; C. M. Scammon, 
Marine Maminals of the N. W. Coast of North America, 1874; W. H. Flower, 
“On the characters and Divisions of the Families of the Delphinidw,” Proc. Zool. 
Soc. 1888, p. 466, and List of the Specimens of Cetacea in the British Museum, 
1885 ; F. W. True, ‘ Review of the Family Delphinide,” Bu//. U.S. Nat. Museum, 
No. 36, 1889; P. J. Van Beneden, Histoire Naturelle des Ceétacés des Mers 
@ Europe, 1889. 
For fossil forms, in addition to the works of Van Beneden, Gervais, and Brandt, 
already cited, the reader may refer to various memoirs published by the former 
writer in the Bull. Ac. R. Belgique and Ann. Mus. R. Hist. Nat. Belg. 
See also R. Lydekker, ‘‘ The Cetacea of the Suffolk Crag,” Quart. Journ. Geol. 
Soc. vol. xlii. p. 7 (1887), and Catalogue of the Fossil Mammalia in the British 
Museum, pt. v. (1887). 
' Gray, Cat. Seals and Whales Brit. Mus. 2d ed. p. 393 (1866). 
