368 [June, 



Notice of the Mya nodulosa, Wood. 

 By Isaac Lea. 



In the examination of the Molluscs of the Imperial Cabinet of Vienna, I ob- 

 served a specimen of the family Naiades, which 1 immediately recognized to be 

 the Mya nodulosa, described and figured by Wood, (General Conchology and 

 Index Testaceorum), and which was placed by me among the nodulous Uniones 

 in my Synopsis. 



The form, thickness and nodulous character of this shell, is so much like that 

 of TJhIo 'pustidosus, nobis, that it has been thought to be the same. I gave it a 

 distinct place in my Synopsis (Ed. 3d, p. 22) with a note doubting it to be an 

 "American species," meaning North American. The locality was unknown To 

 Mr. Wood ; and Mr. Traiinfeld, the able zoologist, under whose charge this de- 

 partment of the Museum is placevl, is entirely ignorant from whence the speci- 

 men was received, it having been in the establishment during the period of the 

 late Mr. Miihlfeld's administration and without locality. Unhappily, therefore, 

 neither of the two known specimens can be traced to their habitat.* The in- 

 spection of the specimen, however, enabled me at once to place the species in 

 its proper position in the system, the teeth, particularly the lateral ones, having 

 equal and parallel strias as in the genus Prisodov., Schum,= Ca.<fte/irt, Lam. The 

 cardinal and lateral teeth are both robust, and of the form of the ponderous sub- 

 rotund Uniones^ but the deeply impressed striae separate it from that genus and 

 place it in Prisodoit. When Schumaker proposed his genus Prisodoiiy and La- 

 marck that of Castalia for the same shell afterwards, there was but one species 

 known. It is true that D'Orbigny proposed two others, qnadrilatera and inflataf 

 but I recognize these only as variations. The genus Prisodun will now, if I be 

 correct in my inductions, consist of three distinct species, each one belonging 

 to a well characterized group, viz. : the plicate, nodulous and smooth divisions, 

 and they will stand in the following order. 



(Plicate.) Prisodon truncates, Schum.=Castalia ambigua, Lam. 



v^S.nooth.) Prisodon Duprei, Lea=Castalia Duprei, Reduz. 



(Nodulous.) Prisodon nodulosus, Lea=Mya nodulosa, Wood. 



The Cominlttoe on Prof. Baird and Mr. Girard's descriptions of new 

 Fishes from the river Zuiii, reported in favor of publication. 



Descriptions of some vew Pishes from the Kiver Zuiii. 

 By S. F. Baiki) and Charles Girard. 



The species of fishes here described as new, were caught in the Zuni River, 

 New Mexico, by Dr. S. W. Woodhouse, while attached as Surgeon and Natu- 

 ralist to the expedition nlCapt. Seetgreaves, for the exploration of Zuni and its 

 tributaries. Full descriptions with figures will be shortly published in the of- 

 ficial report of Capt. Sitgreaves. 



Thpy belong to the Cyprinoid family, and constitute a new genus which we 

 propose to call 



GILA. 



Characterized by its subfusiform and compressed body, its more or less arched 

 back, especially in large individuals, and by its extreme attenuation posteriorly. 

 The peduncle of the tail is rather slender. The head is much depressed, pro- 

 portionally small, its upper outline concave, and its snout elongated. Eyes cir- 

 cular or elliptical. The mouth is small or of medium size, the upper jaw gene- 

 rally overlapping the lower, so as to conceal its cleft from above. No barbels 

 or rudiments of barbels at the angle of the mouth. Pharyngeal teeth oblique, 

 compressed, disposed on two rows with their tip slightly hooked. Branchial 



* The specimen has the fine nacre of the South American Naiades, and I have 

 little doubt but that it inhabits the same country with the other two species. 



