NATURAL SCIENCES OF PHILADELPHIA. 



Genus Micropogon Cuv. 



Micropogon costatus Dekaij. 



Micropogon lineatus Cuv. et Val. 

 Micropogon undulatus Cuv. et Val. 



From the western coasts of North America, three species are at present 

 known : 



Genus Rhinoscion Gill. 



Rhinoscion saturnus Gill. 



Amblodon saturnus Girard. 



Genus Menticirrhus Gill. 



Menticirrhus undulatus Gill. 

 Umbrina undulata Girard. 



Genus Genyonemus Gill. 



Genyonemus lineatus Gill. 



Leiostomus lineatus Ayres, Girard. 



On the LIOSTOMINJE. 

 BY THEODORE GILL. 



In the fourth volume of the original edition of the " Histoire Naturelle," 

 Lacepede has described and figured, from the manuscripts of Mr. Bosc, a single 

 species of fish, for which he formed a new genus, on which he bestowed the 

 name of Leiostomus. The genus in that work is defined as follows : 



"Les machoires denuees de dents, et entitlement cachees sous les levres ; 

 ces memes levres extensibles ; la bouche placee au-dessous de museau ; point 

 de dentelure ni de piquants aux opercules ; deux nageoires dorsales." 



In the first edition of the "Regne Animal," Cuvier expressed a belief that 

 the species on which that genus was founded should be referred to Scicena,* 

 and in his second edition, referred it, as well as the Labrus obliquus of Mitch- 

 ill,! to the subgenus Johnius of Bloch. 



In the fifth volume of the "Histoire Naturelle des Poissons," the genus 

 Leiostomus was adopted, but was simply distinguished by the small size of the 

 anal spine, the feebleness of the " dentelures " of their preoperculum, and 

 the very fine teeth of the jaws." The latter were said to be so fine, that dif- 

 ferent observers had not perceived them, and that Lacepede had therefore, 

 always confiding in the assertions of others, made of one of the species referred 

 to the group a peculiar genus, called leiostomus, or smooth mouth, t The 

 pharyngeal bones were further stated to have paved teeth on their posterior 

 borders. To the genus thus defined were referred two species ; the first was 

 described as Leiostomus humeralis, and regarded as identical with the Labrus 

 obliquus of Mitchill ; the second as the Leiostomus xanthurus of Lacepede. The 

 two species are distinguished only on account of the greater convexity of the 

 nape and the absence of bands and spots in the latter. The teeth of Leiosto- 



* Je ne doute pas que le leyostome queue jaune, Lac, iv. x. i. nc doive aussi etre rap- 

 proche de ce sous-genre (Sciae?ia)," 1 c, vol. ii. p. 298. 



tThis was called Johnius humeralis, Cuv., and was regarded as probably identical with 

 the Perca undulata of Linnseus, which last was afterwards, with more propriety, identi- 

 fied with the species now called Micropogon undulatus. 



JThe Leiostomus obliquus has a band of very fine teeth in the upper jaw, which have 

 been overlooked by Bosc, 



1861.J 



