446 ZOOLOGY 



The bony fishes date back to the Jurassic period, but did 

 not become numerous until the Cretaceous and especially the 

 Tertiary Period. The Green River beds of "Wyoming abound 

 in their remains. 



The Teleosts are divided into eight orders, in an ascending 

 series as follows : Ojnstliomi, Apodes, XematognatM, Scyjiho- 

 vhori, TeUocephali, Pediculati, Lophobranshii and Plectog- 

 nathi. 



Order 1. Opiftliomi. — The fishes of this gi-oup are char- 

 acterized by the separation of the shoulder-girdle from the 

 head. The ventral fins are either aljdomiual or wanting. 

 The tyiDical genus is Xotocantlms, in which the body is elon- 

 gated, with a proboscis-like snout. 



Order 2. Apodes. — In this group, also, the scapulai' arch 



Tig. 403.— Common Eel, AngniU.t acutu'ostris. 



is free from the skull, while the maxillary bones are rudi- 

 mentary. The branchial apertures are unusually small, and 

 there are no ventral tins, while the body is verv long, cylin- 

 drical, snake-like. The order is represented among manv 

 other forms by the common eel {AnguiUa), the couger-eel, 

 and the Jlurwna of the Mediterranean Sea. The conger-eel 

 (Conger oceanicus Gill) ranges from Xewfoundland to the 

 West Indies. Gill, as well as Gi'uither and others, regards a 

 long transparent ribbon-like fish, described under the name 

 of Leptocephalmi as the young of tlie conger-eel. 



The common eel, AngiiiUd. acuHnixtris (Fig. 403). occurs 

 on both sides of the Atlantic, on the Xorth American coast 

 as far south as Cape Hatteras. and in inland rivers and lakes. 

 The sexes do not difEer externally, and internally only 



