202 FISHES. 



III. With two or more free spines in place of first dorsal ; ventrals 



sub-abdominal, of a stout spine and a small ray ; small fishes 

 scaleless or with bony plates. . HEMIBRANCHII, page 209. 



IV. Dorsal fins two, distinct, small, the first of 4 to 7 spines ; ven- 



trals abdominal; teeth feeble or wanting; scales cycloid, 

 silvery. ...... PERCESOCES, page 208. 



V. With the first rays of the dorsal, or the whole first dorsal, of 



simple usually stiff spines; first ray of ventral usually 

 inarticulate (spinous dorsal forming a hump in Cydopterus ; 

 a lamellated sucking disk in EcJieneis, etc., wanting altogether 

 in Aspidophoroides and Gobiesox). ACANTHOPTERI, page 203. 



VI. Fin rays soft and articulated (excepting occasionally one or 



two in dorsal or anal) ; no ventral spines ; scales when pres- 

 ent, usually cycloid. 



* Ventrals jugular; dorsal and anal long, often divided. 



AITACANTHINI, page 208. 



** Ventrals abdominal. 



f Mouth entirely toothless ; abdomen not serrated ; lower 

 pharyngeals falciform, tooth-bearing ; no adipose fin ; 

 head naked ; fresh water. . EVENTOGNATHI, page 211. 



ff Body elongated, scaly ; a series of keeled scales along sides 

 of abdomen; lower pharyngeals united (as in Labridm)', 

 no air duct ; no adipose fin ; no ventral serratures ; one 

 or both jaws or else pectoral fins greatly elongated; 

 chiefly marine. . . SYNENTOGNATHI, page 209. 



fff Head more or less scaly (naked in Amblyopsis, the Cave 

 Blind Fish) ; both jaws fully provided with teeth ; lower 

 jaw usually longest; dorsal far back, nearly opposite 

 anal; no adipose fin, ventral serratures, nor peculiar 

 scales ; chiefly fresh water. . HAPLOMI, page 209. 



ffff Soft -rayed fishes showing none of the above combina- 

 tions of characters ; head naked ; adipose fin or abdominal 

 serratures often present ; dentition and habitat various. 



ISOSPONDYLI, page 210. 

 *## Ventrals entirely wanting. 



\ Jaws with teeth ; vent at the throat ; body oblong ; cave 



fishes HAPLOMI, page 209. 



ft Jaws toothless; vent normal; body serpentiform. 



ANACANTHINI, page 208. 



