CHAPTER (Xa 
CETACEA—WHALES AND DOLPHINS 
Order VI. CETACEA.’ 
Aquatic Mammalia of fish-lke form; tail expanded into 
horizontal flukes; a fatty dorsal “ fin” present in most species ; 
anterior limbs converted into fin-like paddles; posterior linbs 
only represented by skeletal rudiments. Hairy covering re- 
duced to a few isolated hairs in the neighbourhood of the 
muzzle. Nostrils represented by the single or double blow-hole, 
nearly always situated far back upon the skull. Bones of loose 
texture and much impregnated with oil. The skull has a greatly- 
developed facial portion ; supra-occipital bones meeting the frontal 
by overgrowing, or growing in between the parietals; bones 
surrounding the organ of hearing loosely attached to the skull, 
the tympanics of peculiar cowrie-shell form. Coronoid process of 
mandible absent, or very feebly developed. Teeth, when present, 
few or numerous, always of simple conical form, with at most 
traces of additional cusps (Jnia); if absent their place taken by 
whalebone. Cervical vertebrae of short antero-posterior diameter, 
often more or less completely welded together into a single mass. 
Articulations between dorsal and other vertebrae feeble. Scapula 
pecuharly flattened; acromion strongly developed as a rule, but 
arising from a slightly-marked spine; coracoid process generally 
strongly developed. Phalanges of digits always more numerous 
than in other mammals. Clavicles absent. Stomach complex, 
consisting of at least four and often more chambers. Lungs 
simple and non-lobulated. Diaphragm obliquely set and very 
1 See van Beneden and Gervais, Ostéographie des Cétacés ; and for a more general 
account Beddard, 4A Book of Whales, London, Murray, 1900. 
