101. ICOSTEID^E. 619 



Head 7; depth 7. D. 7, 100 to 190; C. 0-5; P. 11; V. 7. (Giinther.) 

 Described from Valparaiso, Chili. A young specimen examined by us 

 from Santa Cruz, Cal., agrees in essential respects, except that the skin 

 x s entirely smooth. The prickles are perhaps acquired with age, other- 

 wise ours may be a different species. T^vo specimens of Trackypterus 

 have also been taken in Puget Sound, but they have not been preserved. 



(Kiier. Wien. Sitzimgsber, xxxiv, 437, 1859, t;if. 1; Gunther, iii, 303.) 



FAMILY CL XCOSTEIDJE. 



(The Ronquils.) 



Body oblong, compressed, naked or covered with small ctenoid or 

 cycloid scales. Head moderate, not externally bony, the opercles un- 

 armed. Mouth moderate, terminal; premaxillary protractile or not; 

 maxillary moderate, without supplemental bone. Teeth small, in bands 

 or in single series; vomer and palatines with or without teeth. No bar- 

 bels. Lower pharyngeals separate. Branchiostegals 6 or 7. Gill-open- 

 ings wide, the membranes free from the isthmus ; gills 4, a slit behind the 

 fourth; gill-rakers slender. Pseudobranchiae large. Pyloric coeca few. 

 Air-bladder present. Lateral line present. Dorsal fin very long, con- 

 tinuous, without distinct spines; .anal long, without spines; caudal tin 

 convex; ventral fins thoracic or subjugular, separate, but very close 

 together, I, 4, or I, 5; pectorals rounded, sometimes fleshy at base. 

 Vent normal, without papilla. Skeleton more or less soft and cartila- 

 ginous. This group, as at present constituted, is composed of three 

 very diverse genera, each of a single species, inhabiting the deeper 

 waters of the North Pacific. It is probably most nearly related to the 

 HalacantMdcB, from which it is distinguished by the presence of pyloric 

 coeca and by the non-labroid dentition. 



(losteidce Jordan & Gilbert, Proc. U. S. Nat. Mus. 1830, 300.) 



a. Body naked, lateral line and fin rays beset with groups of spinules ; skeleton not 



ossified. (Icosteince.) 

 1}. Air-bladder present; teeth in jaws only, in single series, very slender; ventrals 



thoracic, 1, 4 ; caudal peduncle slender ICOSTKUS, 332. 



aa. Body covered with small scales ; no spinules ; air-bladder wanting or rudimentary ; 



ventrals 1, 5. 

 c. Skeleton imperfectly ossified ; lateral line median. (Icichthi/ina>.*) 



d. Teeth in a single series, minute, in jaws only; ventrals thoracic; caudal pe- 

 duncle slender. ICICHTH YS, 333. 



cc. Skeleton ossified; lateral line near the back. (Bathymasterince.) 



e. Teeth in bands, rather strong, on jaws, vomer, palatines, and pharyugeals; 

 veutrals subjugular; caudal peduncle not slender BATIIYMASTKU, 334. 



