46 PROCEEDINGS OF THE ACADEMY OF 



in favor of the "New World." The genera thus peculiar to the different 

 countries are not typical members of the family, but always more or less 

 aberrant. In Europe, are found the Acerina represented by the genus Percis 

 of Klein or Acerina of Cuvier ; the Percarinm represented by a single genus 

 and species, and the still more aberrant subfamily of Asperulince with the 

 genus Asperulus of Klein or Aspro of Cuvier. 



As an offsett to the European genera, there is found in the fresh waters of 

 the United States, a subfamily containing eight genera and numerous species. 

 The genera which America shares in common with Europe are also more 

 developed in the former country than in the latter, and there are species of 

 two allied genera of which no representatives are found in Europe. 



It has been already remarked that the family of Percoids is represented in 

 Europe by three peculiar tribes or subfamilies. In North America there are 

 only two. In the number of widely distinct forms, Europe is therefore richer 

 than America. For the differences existing between the Grystince and the 

 Percince can scarcely be considered as of greater value than those between the 

 Percince on one hand and the Acerina and Asperuli on the other. The differ- 

 ences between the two latter are equally well defined, and it is perhaps doubt- 

 ful if those genera belong to even the same family as the typical Percoids. 

 But if the family of Percoids has more varied types in the old world, that one 

 found in the new exhibits far more numerous modifications, which indicate 

 generic and specific value. 



We now proceed to exhibit the characters of the subfamily of Percince and 

 give a synopsis of all the known genera. 



Percince (Bon.) Gill. 



The body is elongated or oblong ovate, more or less compressed. The head 

 in profile is more or less elongated, conical and compressed. The eyes mostly 

 or entirely in the anterior half of the head, are generally of large size. The 

 mouth is large or moderate, with the gape extending at least to the anterior 

 margin of the eye. The teeth are generally villiform, rarely canine, and cover 

 the jaws, vomer and palatine bones. The intei'maxillary bones have very 

 short ascending processes, and are scarcely protractile. The nostrils are two 

 on each side, forming the angles of a transversely oblong or elongated quad- 

 rangle ; the anterior nostrils are subtubular, and the posterior simple aper- 

 tures. The opercular bones are more or less pectinated or armed with teeth ; 

 the operculum terminates in generally one or more spiniform processes. Th 

 branchiostegal membrane is very deeply emarginated, the sinus extending to 

 between the corners of the mouth ; there the membranes of opposite sides 

 appear to be folded across each other, and leave a very narrow free margin ; 

 there are seven branchiostegal rays on each side, decreasing in size quite 

 uniformly to the external. The scales are of moderate or small size, and on 

 the trunk are pectinated and with a narrow muricated border ; those on the 

 head are either pectinated or cycloid ; the scales on the cheeks are smallest, 

 and occasionally scarcely perceptible. The dorsals are two in number, and 

 are either entirely disconnected or united at the base by a low membrane : 

 the first dorsal is well developed, and supported by from seven to fifteen 

 spines, the longest of which generally equal the height of the second dorsal. 

 The anal fin is generally shorter than the second dorsal ; it has two or three 

 spines and from six to thirteen branched rays. The pectorals are of small or 

 moderate size, in the normal percoid position on the humeral cincture, and 

 have rounded margins. The ventrals are also of moderate size and situated 

 behind the bases of the pectorals ; they have each one spine and five gradually 

 decreasing branched rays ; the innermost ray is free from the abdomen, or 

 scarcely connected to it by an axillar membrane. 



The subfamily of Percince as thus limited is a very natural one. Its charac- 



[Feb. 



