GO. CENTRISCID^. 387 



teiior margiu of orbit; tail longer than head and body together; snont 

 rather shorter than opercle ; supraorbital spine nearly half diameter of 

 eye; coronet well developed, with five spines. D. 19; A. 4. Eings 10 

 -\- 38. San Diego, Cal, and southward ; reaching a length of nearly a 

 foot. 



(Girard, U. S. Pac. R. R. Surv. Fishes, 1858, 34-2.) 



Ordep. S.-HEMIBRANCHII. 



( The Hcmihranohs.) 



Superior branchihyal and pharyngeal bones reduced in number; in- 

 ferior pharyngeals separated. Ventral iins abdominal or subabdominal. 

 Moutli bounded above by premaxillaries only ; interclavicles developed, 

 i^o pneumatic duct to the air-bladder. {Cope.) There are also several 

 striking peculiarities in the structure of the shoulder girdle and the skull, 

 by which these fishes difter from the Acanthopteri^ with which group un- 

 der one name or another they have usually been combined. (>j//j, half; 



^p'^n'<^^ gills.) 



ANALYSIS OP FAMILIES OF HEMIBRANCHII. 



* Bones of head produced into a long tube, which bears the short jaws at its end. 

 a. Body short, compressed, scaly ; no teeth ; spinous dorsal present. 



Centriscid.e, CO. 

 aa. Body elongate; teeth present. 



6. Dorsal spines none ; a long caudal filament ; no scales Fistulakiid.e, G1. 



lib. Dorsal spines present, disconnected ; no caudal lilaraent. 



c. Body covered with ctenoid scales Aulostomatid.e, G'2. 



cc. Body scaleless, with bony shields Aulouhynciud.e^ (V.!. 



** Bones of head moderately produced ; ventrals I, 1 ; dorsal preceded by free spines ; 

 body scaleless, naked or mailed Gasterosteid^, 64. 



Family LX.— CENTRISCID^. 



{The Snipe-fislies.) 



Body compressed, oblong or elevated, covered with small rough scales; 

 no lateral line ; some bony strips on the side of the ba(;k and on the 

 margin of the thorax and abdomen, the former sometinies confluent into 

 a shield. Bones of the skull nuich prolonged anteriorly, forming a long 

 tube which bears the short jaws at the end ; no teeth. Gill-openings 

 wide ; branchiostegals 4. Two dorsal fins, tlie first of 4 to 7 spines, the 

 second of which is very long and strong ; soft dorsal and anal modcM-atc ; 

 ventral fins small, abdominal, of 5 soft rays ; pectorals short ; caudal liu 

 emarginate, its middle rays not produced. Air-bladder large ; pseudo- 



