NATURAL SCIENCES OF PHILADELPHIA. 100 



received from the ancient Greeks the various names of O : jptvo<rx.o?roc, "Ayvos and 

 Kxh^tlvi/fAo; ; when it was classified in the system by Linmeus, the name of 

 Uranoscopus was accepted for its generic appellation, and has been retained 

 by all succeeding naturalists. Many species have been since referred to the 

 geuus, which, although possessed of a similar form, differ considerably in the 

 details of structure. The peculiarity of form is therefore not a generic charac- 

 ter, but indicative of much higher importance ; it is also coincident with many 

 other well marked characteristics, some of which are of much importance, and 

 the combination of which without much doubt indicates that the group is of 

 family value.* 



All the species with the form of the ancient Uranoscopus discovered until 

 within most recent times, had not only the same general and essential, but 

 almost the same positive form as to its details. They chiefly differed in the 

 comparative degree of armature of the head, the presence or absence of scales, 

 the character of the dorsal fin, and the presence or absence of intralabial fila- 

 ments and mental barbels. The differences were evidently of no more than 

 generic value. 



But comparatively, recently, there has been referred to the genus Uranos- 

 copus a fishf which does indeed possess the same general form as the typical 

 species, but differs very materially in the greater elongatiou of its body, as 

 well as in several other essential characters, which the study of the family 

 convinces us are of much more than generic value. It represents, then, not 

 only a distinct natural genus, but a distinct subfamily ; the latter has been 

 recently named Leptoscopina? ; the genus Leptoscopus.% 



Still more recently, there has been referred to the family of Uranoscopoids, 

 a remarkable fish first discovered at the West Indian island of Barbados, 

 which preserves the same general form as Uranoscopus and the same special- 

 ized form as Leptoscopus. Yet this fish is characterized by a feature which 

 may be almost termed anomalous with respect to this family. It has only 

 three ventral rays ! those rays are also simply articulated, and not branched, 

 thus resembling those of the Bleunoids. And yet nature, as if to instruct us 

 as to the little value of any single character which is not a modification of a 

 most important organ, has imprinted on this fish, as has been already re- 

 marked, not only the same general but absolutely all the details of form ex- 

 hibited by Leptoscopus. The only other external generic characteristic which 

 distinguish the West Indian fish from the Leptoscopus are the approximation 

 or separation of the ventral fins,|| and the relative position of the dorsal and 

 anal. In both of these respects, the Leptoscopi approach nearer to the Uran- 

 oscopinae than the Leptoscopinse. The dorsal and anal fins are much elon- 

 gated in both of those genera, in contradistinction to those of the Uranosco- 

 pinse ; but the relative elongation is reversed in the two. In Leptoscopus the 

 commencement of the dorsal is posterior to the vertical of that of the anal, 

 while in Dactyloscopus it is anterior. There are also palatine teeth in Leptos- 

 copus, as in all of the known Uranoscopinaz, whilst in the Dactyloscopi, they are 

 absent. But as if to render the close affinity of the Leptoscopi and the Dacty- 

 loscopi still more evident, there has been recently discovered, at the Island of 

 New Zealand, a fish^ whose almost sole difference from Leptoscopus is also the 



*The Uranoscopoids would form one of the strongest arguments in favor of ihe Agas- 

 sizian doc.rine of the value of form as a family character. That form which results from 

 the similar relations, combinations and proportions of the most important parts, external 

 as we 1 as internal, appears in most case- to be characteristic of natural families. 



t Uranoscopus macropygus Richardson. 



% Leptoscopus Gill, Giinther. 



Dactyloscopus Gill, Poey. 



|| In this respect the Dactyloscopi resemble the typical Uranoscopoids more than do the 

 Leptoscopi. 



11 Crapatalus Guntker. 



1861.] 



