NATURAL SCIENCES OF PHILADELPHIA. Ill 



ventral fins of the others. How numerous are those peculiar features which 

 are possessed by all the members of this family will be evident from the diag- 

 nosis which is now offered. 



TjRANOSCOPOIDiE Gill. 



The body is more or less elongated, conical or subcylindrical, widest and 

 generally highest at the preopercular region ; thence the dorsal and abdominal 

 outlines regularly converge. The scales are very minute, or of moderate size, 

 and sometimes absent. 



The head is cuboid, little narrower, and nearly vertical in front ; the eyes 

 rather small, anterior and superior ; the median infraorbital bones not con- 

 nected with the preopercular. The nostrils are double. The mouth is verti- 

 cal, the lips fringed. The intermaxillary bones have very short posterior 

 processes, and are in front of the maxillary, except at the ends of the latter. 



The branchial apertures are very large, and extend before the pelvic bones. 

 The branchiostegal membrane is doubled in front, and forms a transverse flap 

 between the dentary and angular bones, which conceals anteriorly the branchi- 

 ostegals. There are six rays. 



The branchia? are biserial on the four branchial arches, and there are also 

 pseudo-branchiae. 



The dorsal and anal fins are nearly equal in size, and are always elongated ; 

 the anus is consequently anterior. The caudal is subtruncated. The pecto- 

 rals have oblique bases, and their rays rapidly decrease in length beneath. 

 The ventrals are jugular. 



Head more or less mailed above. Body moderately elongated, Uranoscopin^. 

 Two dorsal fk.s. 



Body scaly. Head mailed above. An intralabial filament. 



Preopercular ?pines below, . . . . 1. Uranoscopus. 



Preopercular spines below. Chin with barbel, 2. Nematagnus. 



Body scaly. Head with a transverse posterior plate, 



whence proceeds a Y-shaped apophysis, . . 3. Upselonphorus. 

 Body naked. Head mailed above, ... 4. Astroscopus. 



Dorsal fin single. 



Body scaly. Head mailed above. 



Dorsal with 3 4 spines, ..... 5. Ichthyoscopus. 



Dorsal unarmed. Lower jaw entire, . . 6. Genyagnus. 



Dorsal unarmed. Lower jaw enlarged beneath, 7. Gnathagnus. 



Body naked, ....... 8. Cathetostoma. 



Head covered with naked skin. Body elongated. 



Ventral rays I. 5, . . . . . . Leptoscopin^e. 



Vomerine and palatine teeth present, . . 9. Leptoscopus. 

 Vomerine and palatine teeth none, . . . 10. Crapatalus. 

 Ventral rays 3, simply articulated, . . . Dactyloscopin.e. 



Vomerine and palatine teeth absent, . . 11. Dactyloscopus. 



Uranoscopin-e (Bon.) Gill. 



The body is moderately elongated, and covered with Yery minute scales, or 

 naked. The lateral line runs abruptly upwards to the dorsal region, is con- 

 tinued under the dorsal fin to its end, and thence deflected downwards to the 

 base of the caudal. 



The head is more or l?ss completely covered with bony plates. There are 

 teeth on the vomerine and palatine bones. 



The anus is in the second third of the total length ; the anal fin moderately 

 elongated and with less than twenty rays. The jugular ventrals are approxi- 

 mated, and have each a slender spine and five rapidly increasing branched 

 rays. 



1861.] 



