120. GADID^ GADUS. 805 



tebrffi, resembling the structure found in 2Ierlueius. This diliereuce, in 

 Dr. Bean's opinion, may necessitate the revival of the genus Tilesia of 

 Swain son. 



{GaduH (jracUiti Tilcsius, Mem. Acad. Imp. St. Petersb. ii, 3.j4, 1810: Gadas ivachna 

 PalLas, Zoogr. Eoss.-Asiat. iii, 182, 1811: Tilesia gracilis Swainsou, 1. c. : Tilesia gracilis 

 Beau, Proc. U. S. Nat. Mus. 1881, 243). 



l)h. Veut in frout of second dorsal; species of small size. {Microgadus* Gill.) 



1241. G. proximus Grd. — Tom-cod. 



Olivaceous above, pale, or slightly translucent, white below; dorsal 

 fins dusky, paler at base; first anal, and ventrals uucolored; second 

 anal dusted with dark points. Head long, convex above, somewhat 

 compressed, with vertical sides; eye moderate, about 5 in head; mouth 

 rather large; maxillary reaching to below pupil; barbel small; teeth 

 in each jaw in a band, the outer row a little enlarged. Gill-membranes 

 a little connected, free from the isthmus. First dorsal highest, some- 

 what falcate, its height three-fifths length of head; first aoal longer 

 and higher than second; pectorals moderate, reaching anal; ventrals 

 filamentous, scarcely reaching anal; caudal slightly emarginate. Lat- 

 eral line very distinct, wavy, high anteriorly, slightly interrupted j)os- 

 teriorly. Vent below first dorsal. Head 4; depth 4§. D. 14-18-19; 

 A. 21-21; V. 6 or 7. L. 1 foot. Monterey to Alaska ; abundant; a 

 food-fish of some importance. 



The Tom-cods {Microgadus) differ considerably from the true cods 

 {Gadas) in the structure of the cranium. The following is Professor 

 Gill's account of the skull of G. liroximus^ the italicised i)ortions indi- 

 cating the differences from Gadus callarias: 



"The cranium is proportionally broader towards the front and less 

 flattened, while the brain-case is flattened below, decidedly sicollen on 

 each side of a dei)ressed sphenoidal groove^ and has an ovate cardi- 

 form shape; the jmraoccipital or epiotic is not produced into an angle 

 behin<l, but is obtusely rounded, and its posterior or outwardlif-descend- 

 ing ridge blunt; the opisthotic is well developed, oblong, and with its 

 re-entering angle high up, and, on a line with it, the surface is divided 

 into two parts — a narrow and flattened one, and a lower expanded 

 one, much swollen; the alisphenoid or i)ro-otic is oblong, acutely emar- 

 ginate in front, swollen from the region of the high anterior sinus, 

 and above a little produced forwards; the gv^-At frontal is a little longer 



*Gill, Proc. Acad. Nat. Sci. Phila. 1865, 69: type Gadua proximus Grd. {juiupo?, 

 small; yadug, Gadus.) 



