OSTEOLEPID 
367 
Family OSTEOLEPIDHh 
Body fusiform, robust, elongated, and somewhat depressed, with 
rhomboidal scales, slightly overlapping, and covered externally with 
a more or less continuous layer of ganoine. Head and opercular 
apparatus with weLU,developed membrane-bones; parietals large 
,,- and separate ; ’ frontals separate, or fused together and with the 
adjoining elements, in which case a median frontal foramen is 
conspicuous; orbits far forwards; interoperculum absent; jugular 
plates comprising one large pair, flanked on either side by a lateral 
series, and with or without a small azygous element in front. 
Dentary bone of mandible fused with well-developed infradentaries in 
the same plane, and forming a thin vertical lamina ; an inner series of 
few large, narrow, shuttle-shaped bones, also fused with the dentary, 
and each supporting a “ laniary ” tooth ; a pair of similar teeth on 
the roof of the mouth, but the marginal upper dentition feeble. 
Teeth conical, with a pulp-cavity, of which the walls are not 
folded, except quite at the base. Pectoral and pelvic fins obtusely 
lobate ; two remote dorsal fins, the first nearly opposite or directly 
opposite to the pelvic pair ; anal fin single ; caudal fin diphycercal 
or heterocercal. 
' In the four typical genera of this family some of the anterior 
rays of each of the fins are relatively robust and covered with 
ganoine. This appearance is due, according to Pander, to the in¬ 
vestment of the rays with true scales. 
Synopsis of Genera . 
I. Scales smooth and punctate. 
A pineal foramen; dorsal fins alternating 
with pelvic and anal; tail heterocercal .. Osteolepis (p. 368). 
A pineal foramen ; dorsal fins opposed to 
pelvic and anal; tail heterocercal. Thursius (p. 373). 
A pineal foramen; dorsal fins opposed to 
pelvic and anal; tail almost diphycercal 
and caudal fin rhomboidal. Diplopterus (p. 37o). 
No pineal foramen; dorsal fins opposed to 
pelvic and anal; tail almost heterocercal.. Megalichthys (p. 378). 
II. Scales sculptured. 
Anterior dorsal fin opposed to pelvic pair: 
tail diphycercal. . . Glyptopomus (p. 389). 
