368 [J UNE, 
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 I 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 Unio pustulosus, nobis, that it has been thought to be the same. I gave ita 
distinct place in my Synopsis (Ed. 3d, p. 22) with a note doubting it to be an 
ss American species,’? meaning North RGnerieans The locality was unknown to 
Mr. Wood; and Mr. Traiinfeld, the able zoologist, under whose charge this de- 
partment of the Museum is placed, is entirely ignorant from whence the speci- 
men was received, it having been in the establishment during the period of the 
late Mr. Muhl]feld’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 striw as in the genus Prisodon, Schum,= Castalia, Lam. The 
cardinal and lateral teeth are both robust, and of the form of the ponderous sub- 
rotund Uniones, but the deeply impressed strie separate it from that genus and 
place it in Prisodon. When Schumaker proposed his genus Prisodon, 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, guadrilatera and inflata, 
but I recognize these only as variations. The genus Prisodon 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. 
(Smooth.) Prisodon Duprei, Lea=Castalia Duprei, Recluz. 
(Nodulous.) Prisodon nodulosus, Lea=Mya nodulosa, Wood. 
The Committee on Prof. Baird and Mr. Girard’s descriptions of new 
Fishes from the river Zuni, reported in favor of publication. 
Descriptions of some new Fishes from the River Zuni. 
By 8S. F. Barrp and Cuartes Grrarp. 
The species of fishes here described as new, were caught in the Tani River, 
New Mexico, by Dr. S. W. Woodhouse, while attached as Surgeon and Natu- 
ralist to the expedition of Capt. Seetgreaves, for the exploration of Zuni and its 
tributaries. Full descriptions with figures will be shortly published in the ot- 
ficial report of Capt. Sitgreaves. 
They 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. 
