NATURAL SCIENCES OF PHILADELPHIA. 503 



2d. Form of the head. 



3d. Direction of the mouth. 



4th. Extent of the branchial aperture. 



5th. Development of a foldjbetween the limbs of the lower jaw. 



6th. Fringed lips. 



7th. Brevity of the spinous portion of the dorsal fin. 



The Leptoscopina? and Dactyloscopinae still further agree with each, still 

 differing from the Blennioids in 



1st. Special form. 



2d. Course of lateral line. 



3d. Special form of head. 



4th. Fringed opercula. 



It agrees with the Blennoiids, and departs from the Uranoscopoids in 

 1st. The structure of the ventrals. 



2d. Simplicity of the pectoral rays. 



With the knowledge that the attributes of the Uranoscopoids above referred 

 to are very peculiar and characteristic, it must be evident that such a com- 

 bination is entitled to much more consideration than the simple agreement in 

 two features, which are by no means peculiar to one group, but shared by 

 many dissimilar families and regarded as of slight importance by Giinther 

 himself. 



In the " Synopsis of the Uranoscopoids," I have remarked that, on account 

 of the special similarity of form, the larger scales, median lateral line, smooth 

 head, extent of the dorsal and anal fins, and the absence of pyloric cseca, 

 " the Leptoscopinse and Dactyloscopinse " together would " be probably re- 

 ferred by some future naturalist to a distinct family." But owing to the many 

 characters shared in common, I doubted the propriety of such a separation. 

 Since the discovery of two other forms, I am now convinced that such a family 

 exists in nature, and therefore now establish it under the name of Leptosco- 



POID.S. 



Family LEPTOSCOPOIDjE Gill. 



Body equally developed above and below the axis, regularly and slowly de- 

 creasing in height to the caudal fin, and behind the abdominal region much 

 compressed. 



Scales cycloid, moderate in size, and regularly imbricated. 



Lateral line anteriorly running along each side of the back and thence 

 decurved and continued along the middle to the base of the caudal fin. 



Head oblong, above nearly plane or slightly convex transversely and not 

 crested, scarcely curved towards the snout. Eyes rather small, more or less 

 directed upwards or on the upper surface of the head, and advanced far for- 

 wards. Suborbital chain enlarged, but no bone connected with the preoperculum 

 as a "stay." Nostrils double. Opercular bones normally developed with 

 regard to each other. Operculum fringed. 



Mouth with the cleft very oblique or subvertical. Intermaxillary bones 

 with moderate or rather short posterior branches, and with the diverging 

 forming the upper portion of the oral arch, the supramaxillars forming the 

 sides. Lips fringed. 



Branchial apertures very large and below in front of the scapular arch, 

 partly covered below by a transverse duplicature or fold of the membrane be- 

 tween the limbs of the lower jaw. 



Branchiostegal rays, six. 



Pseudobranchise, present or absent. 



Dorsal fin entire and very long, with its anterior rays spinous, and the pos- 

 terior articulated. 



Anal fin very long, commencing behind the anus, which is itself in or close 

 behind the breast. 



1862.] 



