282 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



Family AGONID^. 



Agonida; Swainson, Nat. Hist. Fishes, 1839, n, 181. — Gill, Arr. Fam. Fishes, 1872, p. 6 (name only, to em- 

 brace Giinther, n, pp. 211-216). — Jordan and Gilbert, Bull, xvi, U. S. N. M., p. 722. — Gill Proc. U. S. 

 Nat. Mus., xi, 590, 1889. 



Body elongate, or more or less elevated, angular, covered with about eight longitudi- 

 nal series of large, bony, plates, which form a coat of mall; head externally entirely bony, 

 the plates often spinous ; eyes large, placed high; suborbital stay cuirassing the check; 

 mouth terminal or inferior; barbels often present: teeth small, in villiforin bands on the 

 jaws, and often on the vomer and palatines also; gills 3 1 , no slit behind the last; pseudo- 

 branchiae very large, usually extending down the inner side of the opercle; gill rakers 

 small; gill membranes united, free or joined to the isthmus; ventral tins thoracic, close to- 

 gether, imperfect, i, 2 or i, 3; spinous dorsal small, sometimes absent; anal short, similar 

 to soft dorsal, without spines ; caudal narrow, few-rayed ; pectorals entire, with broad base, 

 the rays mostly simple; pyloric caeca few; air bladder none. (Jordan and Gilbert.) 



KEY TO THE DEEP-SEA GENEKA OF AGONIDA. 



I. Spinous dorsal present Agonin.e 



A. Gill membranes joined to isthmus. 



1. Bony plates of body not spiny. 



a. Vomer toothless. No occipital pit [Agonus] 



2. Bony plates of body spinous. 



a. Vomer toothless Podotiiecus 



b. Vomer with teeth. 



Pectorals not notched. Bones of head thin and yielding Bathyagonus 



Pectorals divided by a deep notch into ttt'o portions Xenochirus 



II. Spinous dorsal obsolete. 



A. Gill membranes free from the isthmus Aspidopiioroidin.e 



1. Bony plates of body keeled but spineless AspidopiioROIDES 



PODOTHECUS, Gill. 



Podothtcu8, Gill, Proc. Nat. Sci. Phila., 1861, 259(type, Podotheeus pcrislethus, Gi\l=Agovu8acipen8erinus, Tiles.) 

 Body elongate, fusiform; head long, compressed, armed above; snout protruding much 

 beyond the small, inferior, U-shaped mouth; teeth very small, in villiforin bands; none on 

 vomer or palatines; lower parts of head with barbels; gill membranes united to the isth- 

 mus, not forming a fold across it. Plates of body armed with spiues; spinous dorsal 

 present. Ventral rays i, 2. (Jordan and Gilbert.) 



PODOTHECUS DECAGONUS, (Schneider), Jordan. (Figure 259.) 



Agonus decagonus, Schneider, Bloch's Syst. Ichth., 1801, 105. — Gunther, Cat. Fish. Brit. Mus., II, 215; 



Challenger Report, xxn, 1887, 65.— Collett, Norges Fiske, 1875, 40; Norsk. Nordh. Exped., 44, pi. n, 



figs. 11-12. — LiLLJEiiOHu, Sverig. och Norg. Fisk., 193. 

 Archagonus decagonus. Gill, loc. cit. 



Aspidophorus spinosissimus, Kroyer, Naturhist. Tidsskr., i, 1844, 250. — Gaimard, Voy. Skand., pi. v. 

 Agonus spinosissimus, GCnther, Cat. Fish. Brit. Mus., n. 211. 

 Leptagonus spinosissimus, Gill, Proc. Acad. Nat. Sci. Phila., 1861, 167. 

 Aspidophorus malar moides, Deslongchamps, Mem. Soc. Linn. Norm., ix, 1853, 167. 

 Brachyopsis decagonus, Jordan and Gilbert, Bull, xvi, U. S. Nat. Mus., 727. 

 Podotheeus (Leptagonus) decagonus, Jordan, Cat. Fish. N. Ainer., 1887, 114. 



Body elongate, compressed; head depressed; jaws equal; a pair of spines above the 

 snout, a second above the orbits, a. third on the nape, the latter the largest; barbels very 

 short and thick; scales with very prominent spiues, series of scales between the ventral 

 tins and the vent; 4 between the vent and the aual fin; pectoral fins much longer than 

 head, one-fourth total with caudal. 



Radial formula: D. vi, 7; A. S; P. 14; L. lat. 41. 



Color, yellowish brown, marbled with darker. (Giinther.) 



