1324 BULLETIN OF THE BUREAU OF FISHERIES. 



THE TROUT-LIKE FISHES 



Order Malacopterygii 



Suborder Isospondyli 



Families 

 Elopidm Clwpeido' 



Albulidm Salmonidfe 



MorniyridfB Thijmallidce 



The fishes of this group include many of the most 

 important food and game fishes, such as Tarpons, 

 Trouts and Sahiions, and the Herrings and Sardines. 

 They are distinguished from the Ostariophysi (Case 6) 

 by having the four anterior vertebrae of the spinal 

 column unaltered and separate, and from the Eels 

 (Apodes — Case 9) by the complete and well-developed 

 skull. These characters, together with the soft-rayed 

 dorsal fin and the cycloid scales — rounded in form 

 and with smooth edges — also distinguish them from 

 the Spiny-Rayed Fishes (Order Acanthopterygii — 

 Case 9-14), most of which have ctenoid scales (i. e., 

 scales rounded but with finely toothed edges) and fins 

 partly supported by spines. 



Like the Ostariophysi (Case 9) and the Pikes (Case 

 1 1 ) the Trouts have their ventral fins well separated 

 from the pectorals and placed far back on the abdomen. 

 This is a primitive arrangement and may be seen in 

 all the lower fishes (e. g., the Sharks, Lungfishes, and 

 Ganoids) and contrasts with the more specialized 

 Acanthopterygian condition, in which the ventrals are 

 attached close to the pectorals. 



Ki(_i. 4. — Example of descriptive case-label defining a suborder. 



