34 CETACEA. 



Order CETACEA. 



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

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

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

 united, forming a forked horizontal fin. Nostrils enlarged into 

 blowers. Teats two, inguinal. — Carnivorous. 



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



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



than the arm-hones, suhequal, gradually shorter in the series. — Bal.>s;- 

 NiD^, Catodontid^, Susoidea, OncADiE, Belugid^, Pontopo- 

 HiADiE, Hyperoodontid^, Epiodoxtidje, Zipblhd^. 



II. Pectoral fin elongate, obliquely truncated on the inner side : fingers 5, 



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

 the rest. — ^Inhd^, DelphinA^, Gbampid^, Globiocephalidje. 



m. Pectoral fm elongate, truncated on the inner side ; fingers 4, suhequal, 

 more or less elongate. — AGAPHL^LiD-aE, Megapteeid^, Physalidje, 

 Bal^nopteeip^. 



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



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



and spines into a single mass. 



Mysticetes. Denticetes. 



CATODONTIDiE. 



Gbamped^. 



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



Bal^nidje. Physeterid.^. 



BAL-ff!NOPTERn)-«:. Hyperoodontid^. 



(?) ZlPTTTTT)^. 



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



hinder ones sometimes free. 



Megapterid^. Epiodontid^. 



? ZiPHnDiE. 



Delphinid^. 



Globiocephalid^. 



Orcad^. 



4. Atlas and the other cervical vertebrae entirely free. 



Physalid^. Plataxistidje. 



Agaphelidje. Iniid^. 



pontoporiad^. 



Belugidje. 



