120. GADID^ GADUS. 
805 
tebrae, resembling the structure found iu Merlucius. This diftereuce, in 
Dr. Beau’s opinion, may necessitate the revival of the genus Tilesia of 
Swaiusou. 
(Gadus (jracUis Tilesius, Mem. Acad. Imp. St. Petersb. ii, :3.j4, 1810: Gadas ivachna 
Pallas, Zoogr. Ross.-Asiat. iii, 182, 1811: Tilesia gracilis Swaiusou, 1. c. : Tilesia gracilis 
Beau, Proc. U. S. Nat. Mus. 1881, 243). 
l)h. Vent iu front of second dorsal; species of small size. {Microgadus* Gill.) 
1241. Cr. proximus Grd. — Tom-cod. 
Olivaceous above, pale, or slightly translucent, white below; dorsal 
fins dusky, paler at base; first anal, and veutrals uucolored; second 
anal dusted with dark points. Head long, convex above, somewhat 
compressed, with vertical sides; eye moderate, about 5 iu 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 anal longer 
and higher than second; pectorals moderate, reaching anal; veutrals 
filamentous, scarcely reacliing anal; caudal slightly emarginate. Lat- 
eral line very distinct, wavy, high anteriorly, slightly interrupted i)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) difier considerably from the true cods 
(Gadus) in the structure of the cranium. The following is Professor 
Gill’s account of -the skull of G. proxim us., the italicised portions indi- 
cating the differences from Gadus caUarias : 
“The cranium is proportionally broader towards the front and less 
flattened, while the brain-case is flattened below, decidedly swollen on 
each side of a depressed sphenoidal groove, and has an ovate cardi- 
form shape; the paraoccipital or epiotic is not i)rodnced into an angle 
behind, but is obtusely rounded, and its posterior or outwardly-descend- 
ing ridge blunt; the opisthotic is well develoi)ed, 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 pro-otic is oblong, acutely emar- 
giuate in front, swollen from the region of the high anterior sinus, 
and above a little produced forwards; the great /roa/aZ is a little longer 
*Gill, Proc. Acad. Nat. Sci. Phila. 1865, 69: type Gadus proximus Grd. 
small; yadog, Gadus.) 
