2054 Bulletin 4.7, United States National Museum. 



Aspidophorus spinosissimux, KKOYER, Ichth. liidrag. Naturhist. Tidskr., i, 250, 1844-45, 

 Greenland; KROYER, Gaimard, Voyages en Scand., etc., Zool. Atlas, Poiss., pi. 5, figs. 



2a~2d, 1845. 

 Aspidophorusmalarmoides, DBS LONGCHAMPS, Mem. Soc. Linn, de Normandie, tome ix, 167, 



1853. 

 Aspidophorus decagonus, CUVIER & VALENCIENNES, Hist. Nat. Poiss., iv, 223, 1829; J. 



REINHARDT, Sr., Overs, over det. Konigl. Danske Vid. Selsk. s. Fork., 53, 1830-1832; 



KROYER, Ichth. Bidrag. Naturhist. Tiddskr., i, 243, 1844-45; KROYER, Gaimard, Vo> 



ages en Scand., Lapnouie, etc., Zool. Atlas, Poiss., pi. 5, figs. la-Id, 1845. 

 Agonus spinosissimus, GUNTHER, Cat., n, 214, 1860. 



Leptagonus spinosissimus, GILL, Proc. Ac. Nat, Sci. Phila., xiu, 1861, 167. 

 Brachyopsis decagonus, JOEDAN & GILBERT, Synopsis, Fishes N. A., 727, 1883. 



767. PODOTHECUS, Gill. 



Podothecus, GILL, Proc. Ac. Nat. Sci. Phila, xiu, 1861, 77, 259 (peristethus= acip'enserinuti). 

 Paragonus, GILL, Proc. Ac. Nat. Sci. Phila. xm, 1861, 167, 259 (acipenserinus) . 



Body tapering nearly uniformly from head to caudal, about as high as or 

 higher than wide anteriorly; depth about 6 to 8 inches in length; head 

 about 4, compressed; plates in dorsal series about 35 to 40, 4 or 5 pairs 

 between occiput and first dorsal fin; gill membranes joined to isthmus, 

 without free fold; no scattered barbels under lower jaw or on brauchioste- 

 gal membranes ; 2 complex groups of barbels on under side of tip of snout, 

 another group at each angle of mouth; usually a few barbels at sides of 

 pores under lower jaw; tip of snout with usually 2 pairs of .sharp slender 

 spines, the anterior directed forward, the posterior outward and back- 

 ward. Mouth small, inferior, snout projecting far beyond it. Teeth on 

 both jaws few and weak, sometimes wanting on 1 or both jaws; none 

 on vorner and palatines; plates of body spinous; 1 pair of supraocular 

 and 1 pair occipital spines; both dorsals present. This genus is very 

 close to Agonus, differing mainly in the spinous plates of the body. The 

 numerous species differ much among themselves, (itovs, foot; Qijujf, 

 box; from the groove for the receptacle of the ventrals which appears 

 through the shrinking of the naked skin in preserved specimens.) 



a. Plates on caudal peduncle all or nearly all armed each with a spine. 



b. Barbels below snout very numerous and large ; angle of mouth with many bar- 



hels. ACCIPITER, 2409. 



c. Dorsal raysVIII-9; teeth well developed; fins all very high, the pectoral 



emarginate in the adult, its longest rays If in head; ventral long; anal 



rays 10. 



cc. Dorsal rays XI-8 ; teeth present ; fins moderate; pectoral not emarginate ; 

 ventral short; anal rays 9. HAMLINI, 2410. 



bb. Barbels comparatively few and slender. 



d. Dorsal rays VIII-8; teeth in upper jaw almost obsolete; fins moderate; 

 pectoral not emarginate, 1 in head; ventral very short; anal rays 9. 



GILBERTI, 2411. 



dd. Dorsal rays IX-6; fins small; ventrals long; sides and top of head with 



very large crests ; anal rays 6. THOMPSONI, 2412. 



aa. Plates on caudal peduncle mostly not ending in spines; fins rather low, the anal 



rays 7 or 8. 



e. Teeth well developed; barbels below snout and at angle of mouth long and 



numerous. ACIPENSERINUS, 2413. 



ee. Teeth wanting in the adult; barbels rather small and sparse; body not 



everywhere deeper than wide; the caudal peduncle very long, slender 



and depressed. VETERNUS, 2414. 



