486 THE FUR SEALS OF THE PEIBILOF ISLANDS. 



This species seems to differ from Gymnelis viridis in the more backward insertion 

 of the dorsal, at least an eye's diameter behind the pectoral, and in the presence of a 

 large, jet-black ocellated spot on the dorsal over the vent. The small white spots 

 on anterior part of the body were apparently taken by Dr. Collie, its discoverer, for 

 "very small scales." The species is naked, and this discrepancy led Eichardson to 

 redescribe this form as Gymnelis viridis var. unimaculatus. Richardson's figures of 

 the two forms (Last Arctic Voyage) are excellent. Whether they are really distinct 

 remains to be proved. 



Family LYCODAPODID^E. 



201. Lycodapus eztensus Gilbert. 

 From off Unalaska. 



202. Lycodapus parviceps Gilbert. 

 From near Unalaska. 



Family GADID^E. 



203. Lota maculosa (Le Sueur). 



In the Yukon, Nushagak, and other rivers of northern Alaska. 



204. Theragra chalcogramma (Pallas). 



Unalaska, St. Paul, St. George, Bering Island, Petropaulski; station 3651, off 

 Eobben Reef, depth 20 fathoms. Everywhere abundant. The following notes are 

 from adult specimens : 



Olivaceous above, sides silvery, with two interrupted stripes of dark, brassy olive 

 along sides; these irregular on their edges, each about half width of eyej a trace of 

 a third similar stripe below anteriorly, the stripes very irregular; back mottled 

 Dorsal plain dark olive; pectoral quite dark; lower fins ashy; caudal ashy olive. 



D., 12, 14, 18; A., 19, 20. Ventral nearly to vent; pectoral to anal, IJ in head; 

 eye 5; snout 3^; maxillary 2i. Head 4; depth 6. 



The Alaskan pollack seems to be the type of a distinct genus, for which Mr. Lucas 

 suggests the name of Theragra. The following is Mr, Lucas's note on the genus : 



The Alaskan pollack differs from the Atlantic pollack in having 19 precaudal and 33 caudal 

 vertebra?, instead of 23 precaudals and 32 caudals; the bodies of the vertebr83 are also slightly longer 

 and more deeply sculptured in the Alaskan fish and the spinous process of the anterior dorsals less 

 elevated. 



The greatest differences between the two speciesj however, are to be found in the gill covers, for 

 the suboperculum of the Alaskan pollack is thick, smooth, and dense, instead of being tljin and squa- 

 mous. The postclavicle is also similar in structure, while its proximal portion is subcircular in the 

 Alaskan species and rhomboidal in the Atlantic. This ivory-like character of the suboperculum and 

 post clavicle is so marked [in the Alaskan form] that it serves to distinguish these bones at a glance, 

 being entirely different from what is found in the corresponding bones of other gadoids. 



The vertebral differences between the two fishes are merely differences of degree and of specific 

 value only, but the differences between the subopercula and postclavicula are differences in kind, 

 distinguishing the Alaskan pollack not only from the Atlantic pollack, but from other gadoids. This 

 being the case, it is proposed to establish a distinct genus for the Alaskan pollack, and the name 

 Theragra is proposed for this genus. (F. A. L.) 



205. Gadus macrocephalus Tilesius./ Codfish. 



Everywhere common; taken at Karluk, Belkofski, Unga, Unalaska, St. Paul, St. 

 George, Bering Island. 



