132 PROCEEDINGS OF THE ACADEMY OP 



On DACTYLOSCOPTJS and LEPTQSCOPTJS, two New Genera of the Family of 



Uranoscopidae. 

 BY THEO. GILL. 



Dactyloscopus Gill. 



Body elongated, with the dorsal and abdominal outlines slowly converging 

 to the caudal fin. Scales large, regularly imbricated. Lateral line straight, 

 and running along the middle of the side. Head oblong, subcubical and smooth. 

 Preopercle entire, opercle radiatedly fringed behind. Mouth nearly vertical. 

 Tongue thick, narrowed anteriorly, attached to the floor of the mouth. Labial 

 velum without a barbel. Anus a short distance behind the base of the pectoral 

 fins. Dorsal fin subequal, single and very long, commencing above or before 

 the anus, and continued almost to the base of the caudal. Anal fin commen- 

 cing behind the anus, and with the same form and termination as the dorsal. 

 Caudal fin small and narrow, posteriorly subtruncated. Pectoral fins suban- 

 gular. Ventral fins jugular, closely approximated, and each with three stout 

 simple and articulated rays. 



D. tridigitatus Gill. The head from the snout to the margin of the 

 opercle forms about a fifth of the extreme length. 



The greatest height is equal to a seventh of the same. The caudal fin forms 

 an eighth. The dorsal commences over the lower angle of the base of the 

 pectorals, or immediately before the margin of the operculum. 



D 40, A 34, C 1, 5, 5, 1, P 13, V 3. 



The color, as far as preserved, is gray, marbled with white. 



Three specimens were obtained by the describer at the island of Barbadoes. 

 The largest is slightly more than three inches in length. They are all in a bad 

 state of preservation. 



This is a most interesting genus, from the unusual combination of the char- 

 acters which it presents. From all the species that have been hitherto referred 

 to the genus Uranoseopvs, it is at once distinguished by the entire absence of 

 teeth on the palatine arch, and by the presence of only three rays to each of the 

 ventral fins. Notwithstanding these anomalous characters, it presents so close 

 a resemblance in general form to a species that has been described by Sir John 

 Richardson, as Uranoseopvs macropygns, that it might readily be referred to the 

 genus by a casual observer. The same smooth head, the same gradually taper- 

 ing body, the long dorsal and anal continued to the base of the caudal, the re- 

 gularly imbricated scales, the straight and median lateral line, and the fringed 

 operculum, are seen in both genera. In most of these characters, the two 

 fishes are unlike any of the other Uranoscopi. Dactyloscopus is again distinguish- 

 ed from the so-called Uranoscopus macropygus. besides the two characters that 

 have been already pointed out by the relative length of the dorsal and anal fins, 

 and by the relative situation of the ventrals to each other. In the first described 

 by Richardson, the anus is even more forward than in the West Indian species, 

 and the anal fin commences immediately behind. The dorsal begins at some 

 distance behind the nape, and over the sixth or seventh anal ray. The ven- 

 trals are also seperated from each other by a wide interval. In the genus 

 Dactyloscopus the dorsnl commences above the lower angle of the pectorals, and 

 therefore considerably in advance of the anal fin. The ventrals are also closely 

 approximated to each other, and in this respect, resemble the typical Uranos- 

 copi. Uravoscopus macropygus lias a smaller operculum than Dactyloscopus tricli- 

 gi'alus, and this operculum is also triangular and fringed along its upper mar- 

 gin. The former species having been placed in the genus Uranoscopus, it is, of 

 course, to be understood that it is provided with teeth on the vomer and pala- 

 tine bones. As it is advisable that it should be erected into a distinct genus, 

 the name of Leptoscopus is now conferred on it, and the comparative characters 

 of the two genera are herewith given. 



[April, 



