282 DEEP-SEA PISHES OF TUE ATLANTIC BASIN. 



Family AGONID^^. 



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

 brace Giinther, ii, 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 longitiuli 

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

 the plates often spiuous; eyes large, placed high; suborbital stay cuirassiug the cheek; 

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

 jaws, and often on the vomer and jKilatiiies also; gills 3i, no slit behind the last; jiseudo- 

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

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

 gethci-, 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 cieca few; air bladder none. {Jordan and Gilbert.) 



KEY TO THE DEEP-SEA GENERA OF AGONIDA. 



I. Spinous dorsal present Agonin.e 



A. Gill membranes joiiietl to isthmus. 



1. Bouy j)l:ites of body not spiny. 



a. Vomer toothless. No occipital pit [Agonus] 



2. Bony plates of body spinous. 



a. Vomer toothless Podothecus 



b. Vomer with teeth. 



Pectorals not notched. Bones of head thin and yielding Bathyagonus 



Pectorals divided by a deep notch into two portions Xenochirus 



II. Spinous dorsal obsolete. 



A. Gill membranes free from the isthmus Aspidophoroidin.e 



1. Bouy plates of body keeled but spineless Aspidophokoides 



PODOTHECUS, Gill. 



Podothecus, Gill, Proc. Nat. Sci. Phila., 1861, 259 (type, Podothecus peristethus, Gi\\=:Agonus adpenserimts, Tiles.) 

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

 beyond the small, inferior, U-shaped mouth; teeth very small, in villiform 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 spines; spinous dorsal 

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



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



Agonus decagonus, Schneider, Bloch's Syst. Ichth., 1801, 105.— GiJNXnER, Cat. Fi.sh. Brit. Mus., ii, 215; 



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



iigs. 11-12. — LiLLJEHORG, Sverig. och Norg. Fisk., 193. 

 Arvhagoniis decagonus, Gill, loc. dt. 



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

 Agonus spinosissimus, GItnther, Cat. Fish. Brit. Mus., ii, 214. 

 Leptagonus spinoshshnus, Gill, Proc. Acad. Nat. Sd. Phila., 1861, 167. 

 Aspidophorus malarmoides, Deslongchamp.s, Mem. Soc. Linn. Norm., ix, 1853, 107. 

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

 Podothecus (Leptagonus) decagonus, Jordan, Cat. Fish. N. Amer., 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 spines, series of scales between the ventral 

 lins and the vent; 4 between the veut and the anal fin; pectoral tins much longer than 

 head, one-fourth total with caudal. 



Radial formula: I), vi, 7; A. 8; P. U; L. lat. 41. 



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



