34 



Order CETACEA. 



Teeth all similar, conical, sometimes not developed. Palate often 

 furnislied with transverse plates of baleen or whalebone. Body fish- 

 shaped, smooth, bald. Limbs clawless ; fore limbs fin-shaped ; hinder 

 united, forming a forked l^orizontal fin. Nostrils eiiarged into 

 blowers. Teats two, inguinal. — Carnivorous. 



They may be divided by the form of the pectoral fin; thus : — 



I. Pectoral Jin broad, truncated or rounded at the end ; fingers 5, shorter 



than the arm-bones, subeqtial, gradually shorter in the series. — ^Bax^- 

 NrojB, Catodontid^, Susoidea, Okcad^, Bblugidje, Pontopo- 

 BiAD^, Hypbkoodontidje, Epiodontid^, ZlPHnD^. 



II. Pectoral fin elongate, obliquely truncated on the inner side ; fimgers 5, 



elongate, longer than the arm-bones, the second and third much longer than 



the rest. — iNnDiE, DELPHINIDai, GbAMPIDJB, GLOBIOCBPHALIDiE. 



m. Pectoral fim elongate, truncated on the inner side ; fimgers 4, suhequal, 

 more or less elongate. — AGAPlLS)LiDiE, Megaptbeid^, PHTSALiD.ffi;, 



BALiBNOPTEBIDiB. 



By the adhesion or non-adhesion of the cervical vertebrs9, thus : — 



1. Atlas distinct, the other six cervical vertebrae united by theu- bodies 



and spines into a Single mass. 



Mysticetes. Denticetes. 



Catodontid^. 



GllAMPID.ffi;. 



2. Atlas and cervical vertebrEB all united into one solid mass. 



BALiENroJE. PhysEteeid^. 



BAL^NOPTBErD.a;. HYPBROODONTIDiE. 



(?) ZiPSUBJE. 



3. The atlas, axis, and generally one or two other vertebrae united ; the 



hinder ones sometimes free. 



MBGAPTEErDiE. EpiODONTIDiE. 



? ZiPHnn^. 



DELPHrNID^!. 



GlOBIOCEPHALIDjE. 



OECADiE. 



4. Atlas and the other cervical vertebriie entirely free. 



PhYSALID.*!. PLATANISTIDiE. 



AOAPHELIDiE. InIID^. 



PONTOPORIAD^. 



