246 THE DACTYLOPTEROIDEA GILL. 



with the true bones; with tbe posterior lateral limbs of the casqne, 

 composed of the post-temporal aud the couuecting bones, projecting 

 backwards in spiniforni extensions on each side of the first dorsal fin. 



Eyes mostly in the anterior half of the head, entirely lateral, and 

 widely separated from each other. 



Nostrils double, the two openings separated by a narrow bridge and 

 inclosed in a common cavity in the casque above the preorbitals. 



Suborbitals peculiarly developed, aud with a free peripheral margin 

 except at the pontinal; the preorbital very long, extending forwards 

 and articulated with or nearly meeting its fellow of the opposite side, 

 articulating behind with two bones, one above its angle (the fourth 

 suborbital) forming most of the margin and floor of the orbit, the 

 other (the second suborbital) inferior entering into the lower margin 

 of the head ; the latter articulates with a small special bone (the third 

 suborbital or pontinal) which articulates with the inner angle of the 

 preoperculum. Behind the orbit is a small, rather narrow postorbital 

 connected with the spenotic. 



Opercular apparatus peculiar; the opereulum small, flexible, subcir- 

 cular or subtriangular, and covered with scales ; suboperculum almost 

 membranous, mostly concealed, and partly behind and below the 

 operculum ; interoperculum reduced to a small bone connected by lig- 

 ament with the lower jaw, and remote from the interoperculum, mostly 

 folded under the anterior margin of the preoperculum.* 



Preoperculum enormously developed, dividing into two long narrow 

 branches, a sul)vertical and a horizontal, aud terminating behind in an 

 elongated spine continued from its horizontal atid underlying the 

 pectoral fin. 



Mouth small, opening directly under the snout, and with its cleft 

 nearly parabolic. 



Jaics normally developed ; the intermaxillines with moderately elon- 

 gated pedicles, compressed and conv^erging behind, and with a broad 

 dentigerous surface in front; the supramaxillines forming the lateral 

 borders of the mouth, with the sella? convex on the anterior surface 

 and fitting into the concave surface of the intermaxillines, and with the 

 posterior limbs but moderately expanded. 



Teeth pisiform or obtuse and in bands on the jaws, but none on the 

 palate. 



Lips slightly fleshy. 



Tongue small, reduced to a smooth, narrow, fleshy convexity of the 

 floor of the mouth. 



*Cuvier aud Valenciennes wrongly describe the suboperculum and interoperculum 

 as disappearing almost at the membrane. Their words are, " le sous-opercule et 

 I'intoropercule disparaissent presque dans la membrane "(p. 123). The interoper- 

 culum, however, has its normal relations with the lower jaw, and, although small, is 

 distinctly developed. 



It was correctly determined by C. Dareste, in 1872 (Comptes Rendus Acad. Sc, 

 1872), and by Sorensen (Naturhist. Tijdskr., 1884, pp. 75-78). 



