172 [September, 



and its anterior margin is situated nearer the tip of the snout than the insertion 

 of the caudal fin. The latter is forked. 



D 14 ; A 10 ; C 6, 1, 8, 8, 1, 5 ; V 9 ; P 17. 



The sub-opercle is well developed ; the eye is sub-circular, its diameter being 

 contained four times and a half in the length of the side of the head. The snout 

 is rather pointed, sub-conical, and the mouth, which is small, placed entirely in 

 advance of the orbit. Twelve longitudinal rows of scales may be counted upon 

 the greatest depth. The scales upon the dorsal and lateral regions are provided 

 with a black dot or spot upon the anterior part of the exposed portion of the scale. 

 Greatest length of specimens observed, six inches and a half. 



This species was collected with the preceding, under the same circumstances 

 and in the same locality. 



4. MoxosTOMA CAMPBELLi. Sub-fusiform and clougatcd like the preceding spe- 

 cies, which it resembles in its general outline, and in the proportions of the head 

 and depth of the body towards the total length. The snout is likewise pointed and 

 sub-conical, but the eye is much larger and the sub-opercle very exiguously de- 

 veloped. The position and shape of the fins do not differ materially from the 

 preceding species, with the exception of the caudal, which is concave posteriorly 

 instead of being forked. 



D 15 ; A 10 ; C 5, 1, 8, 8, 1, r> ; V 9 ; P 15. 



The scales are smaller than in M. kennerlii ; thirteen rows instead of twelve 

 are to be observed upon the region of greatest depth. 



Specimens were collected in Live Oak creek, Texas, by Dr. C. B. Kennerly, 

 under Major Emory, and in Devil's river, by John H. Clark, under Col. Graham. 

 The species, therefore, belongs to the basin of the Rio Grande del Norte (Rio 

 Bravo). 



As regards the generic features of 



U fl TT- r^ T-T ^-^ ri m 



Ptychostomus, Agass. 



it fell within our observation that the height of the dorsal may be either equal to 

 its length or a little higher than long, and that the wing-like expansions of the 

 pharyngeals is anything but characteristic of this genus. The transverse folds 

 or ridges upon the lips are shared by Moxostoma, though in a lesser degree. The 

 inferior lip is but slightly lobed. The mouth, however, is much more protrac- 

 tile and directed more downwards. The head is short and stout ; the scales large 

 and of the same size anteriorly and posteriorly. Finally, the conspicuous 

 lateral line will at once .distinguish it from Moxostoma. 



1. Ptychostomus congestus. Catostomus congesins, B. & G. Proc. Acad. Nat. 

 Sc. Philad. vii. 1854, 27. This species comes under this head and not of 

 Moxostoma. 



From the Rio Salado, Texas. John H. Clark. 



2. Ptychostomus albidus. The general physiognomy of this species reminds 

 of us P. congestus, although the body is more slender and the head more elongated. 

 The mouth is a great deal larger, as are also the scales. Greyish white above ; 

 greyish silver beneath. 



Collected by Lt. D. N. Couch, U. S. A., in the Rio San Juan, near Monterey, 

 New Leon. 



3. Ptychostomus haydeni. The head is contained five times and a half in 

 the total length. The body is sub-fusiform, very regular in its outline. The 

 eye is sub-circular and moderate in its development ; its diameter being con- 

 tained five times in the length of the side of the head. The opercle is largely 

 developed, whilst the sub-opercle is small, a character Avhich is more or less 

 generical. The anterior margin of the dorsal fin is much nearer the tip of the 

 snout than the base of the caudal. The height of that fin is a little more than 

 itslength; its upper margin is sub-concave. The caudal is forked. The origin of the 



