NATURAL SCIENCES OF PHILADELPHIA. 15 



L Dorsal subcentral, above or nearly above the ventrals Argentina. 



A. Branchiostegal rays 8. Mouth rather large. Ventrals 

 under the front or in advance of dorsal. 



Scales of the male villose or pointed, in a lateral 



band. Pectoral and ventrals much developed Mallotus. 



Scales alike and simple in both sexes. Pectorals 



and ventrals moderate Osmerus. 



A A. Branchiostegal rajs 6. Mouth small; maxillar ceas- 

 ing under front of eyes. Ventrals nearly under 



middle of dorsal Hypomesus. 



AAA. Branchiostegal rays 6. Mouth very small ; maxillars 

 not extending to eyes. Ventrals inserted under rear 

 of or behind the dorsal. 



Scales cycloid Argentina. 



Scales with exposed surface spinigerous Silus. 



II. Dorsal far behind, above anus Retropinn.e. 



Branchiostegal rays 6. Scales cycloid Retropinna. 



The genus Thaleichthys, of Girard, has not been adopted, it appearing to be, 

 as Dr. Ayres has already shown, identical with Osmerus. The latter gentleman 

 has remarked, <; that the very species which the describer takes as the type of 

 Thahichthys, has occasionally teeth on the palatines well developed ; and one 

 specimen in my possession shows even denticulations on the maxillaries." 



There is a very considerable analogical resemblance between the group of 

 Argentinae and the Salmonine genus Argyrosomus of Agassiz, a resemblance 

 more especially manifested between the genus Hypomesus and the American 

 Argyrosomus albus {Coregonus albus, Les.) and the A. albula (Coregonus albulus, 

 Val.) of Northern Europe. The likeness, however, appears simply to be one of 

 analogy, and not indicative of close affinity. 



Appendix to the Synopsis of the Subfamily of PERCIN2E 



BY THEODORE GILL. 



Since the publication of the " Synopsis of the Subfamily of Percinae," we 

 have become acquainted with two quite distinct generic types which are now 

 referred to their places in the system. This appendix will consequently perfect 

 to date the synopsis, and exhibits the condition of our present knowledge of 

 the Percinas, with the exception, perhaps, of the relations of the Labrax lyiuy 

 of Basilewski. That species does not appear to belong to Labrax, but rather 

 to an unnamed genus, but the description is too defective to admit of its pro- 

 per classification. 



Genus Chorististum Gill. 



Liopropoma? sp. Poey, Memorias sobra la Historia Natural de la Isla de Cuba 

 vol. ii. 



Body fusiform, with the caudal peduncle high and compressed. Head rather 

 elongated, conic in profile and acute in front, but with the outline slightly 

 curved. Lower jaw protuberant. Teeth villiform on the jaws, vomer and pala- 

 tine bones. Preoperculum entire. Operculum armed with two spines. Scales 

 on the whole body, except the muzzle. Dorsal fins entirely separated; the 

 first with five spines diminishing from the second; the second dorsal with a 

 single spine. Anal armed with three graduated spines, and with the soft 

 portion elevated backwards. Caudal subtruncated. Lateral line anteriorly 

 arched. 



Type. Cborististium rubrum, Gill. 



Syn. Liopropoma? rubre, Poey. Memorias sobra la Historia Natural de la 

 Isla de Cuba. Tomo ii., p. 



1862.] 



