724 CONTKIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



the isthmus; ventral fins thoracic, close together, imperfect, I, 2 or T, 3; 

 spinous dorsal small, sometimes absent; anal short, similar to soft dor- 

 sal, without spines; caudal narrow, few-rayed; pectorals entire, with 

 broad base, the rays mostly simple; pyloric coeca few; air-bladder 

 none. Small fishes, chiefly of the Arctic Seas. Genera about 10 ; spe- 

 cies about 16. They feed chiefly on Crustacea, and are often found at 

 considerable depths. 



{TriglidcB, group Cataphracti pt. Giinther, it, 211-216.) 



a. Spinous dorsal obsolete ; gill-membranes free from tbe isthmus. (Aspidophoroidince. ) 



ASPIDOPHOROIDES, 381. 

 aa. Spinous dorsal present. 

 i. Gill-membranes free from the isthmus; lower jaw projecting, 

 c. Body extremely elongate; snout forming a tube; chin with a single long 



barbel Siphagonus, 382. 



cc. Body fusiform, less elongate; snout not forming a tube; chin without barbel. 



Brachyopsis, 383. 

 bb. Gill-membranes united to the isthmus, lower jaw included. 

 d. Bony plates of body without spines. 



e. Vomerine teeth none; no occij)ital pit Agonus, 384. 



ee. Vomerine teeth present ; a deep pit at the occiput Bothragonus, 385. 



dd. Bony plates of bodj^ ending in spines. 



/. Vomerine teeth present Odonto pyxis, 386. 



ff. Vomerine teeth none Podothecus, 387. 



3§1.— ASPIDOPHOROIDES Lac^pMe, 

 {Anoplagonvs Gill.) 



(Lac^pfede, Hist. Nat. Poiss. iii, 228, 1802 : type Aspidophoroides tranquebar Lac. = Cottus 

 monopterygius Bloch.) 



Body very long and slender, subterete, octangular, tapering into a 

 very long six-sided tail. Head slender, short, with large eye; mouth 

 small, terminal; jaws and vomer with villiform teeth. Dorsal fin 

 single, without spines, very small, inserted nearly opposite the still 

 smaller anal; other fins small; bony plates of body keeled, without 

 spines; gill-membranes broadly united, free from the isthmus. [dff-U, 

 shield; (popiio^ to bear; e:(5o?, appearance.) 



a. Nasal spines very strong. 



1109. A. monopterygrius (Bloch) Storer. 



Brownish, obscurely banded with darker; pectorals, dorsal, and cau- 

 dal mottled or barred. Head triangular, much narrowed anteriorly; 

 nasal spines very large, diverging, inserted near tip of snout; no other 

 spines anywhere; eyes very large, longer than snout; supraocular 

 ridges very high; a ridge extending backward from eye along tem- 



