1856.] 213 



provided with a barbel upon its angle, and inserted upon the extremity of the 

 maxillary bone. Eye approximating the upper surface of the head, and rather 

 moderate in size. The isthmus is wide. The insertion of the ventrals is even 

 with a vertical line drawn from the anterior margin of the dorsal fin. The 

 latter is higher, and the anal deeper than long. The scales are large, and the 

 lateral line nearly straight along the middle of the flanks. The pharyngeal 

 bones are pretty stout upon their convexity which is very slightly expanded, 

 whilst the upper and lower branches are nearly equally developed, the latter 

 however, more slender. The teeth are stoutish, compressed, of the prehensile 

 kind of the hooked type, generally without grinding surface. Sometimes, 

 however, a grinding surface may be observed upon some of the teeth which are 

 subject to some variations being compressed or else subconical, generally 

 hooked and occasionally conical. They are disposed upon a single row : 4 4 . 



1. Ceratichthys biguttatus, Bd. Semotilus biguttattis, Kirtl. Bost. Journ. 

 Nat. Hist. III. 1840, 344. PI. v. fig. 1. Leuciscus biguttatus^ Dekay, Fauna of 

 N. y. III. 1842, 214. Storer, Synops. 1846, 161. 



From Yellow Creek, a tributary of the Mahoning. J. P. Kirtland. 



2. Ceratichthys amblops. Rutilus amblops, Rafin. Ichth. Ohiens. 1820, 51. 

 Falls of the Ohio. Rafinesque. 



3. Ceratichthys leptocephalus. A species easily to be distinguished from 

 its congener, by its small head which enters four times and a half in the 

 total length. The body itself is proportionally shorter than in C. amhlops 

 especially. Its scales are likewise larger than in the latter species. The color 

 is of a uniform blackish grey above, and greyish white beneath. 



Specimens were collected at Salem, N. C, by J. T. Lineback and School, and 

 preserved in the Museum of the Smithsonian Institution. 



NocoMis BELLicus. It is a more bulky and deeper fish than its con- 

 gener from Nebraska. And what is still more characteristic, its head is 

 smaller, hence its mouth smaller also. We could not detect the small teeth 

 constituting the inner row, but supposed they got lost in the preparation of the 

 pharyngeal bones. At any rate, whetlier lost or entirely absent, we have here 

 a second species of the genus Nocomis. Color reddish above ; reddish yellow 

 beneath, with an obsolete black spot upon the base of the caudal. 



Caught in the Black Warrior River, Ala. Prof. A. Winchell. 



Description of the Byssus in the genus Unio. 

 By Isaac Lea. 



Professor Kirtland published in the American Journal of Science for July. 

 1840,* some observations he had made on the anatomical and physiological 

 characters of the Naiades, and was the first a few years before to have noticed, 

 that at least some species of Unio, when very young, were anchored to some 

 foreign substances by " a small silky filament" attached to the foot. I had 

 casually observed the fact in a single instance, in Unio complanaius from the 

 Schuylkill, but had not the opportunity of again witnessing it. The Professor 

 followed up his discovery at different periods, and found thus attached the young 

 of the following species ; viz., zigzag, elegans, dehiscens, ebenus, crassus, foliatus, 

 pyramidatus, crassidens and gibbosus. 



The fact at the time was considered of great interest, and it was verj' much 

 desired that further observations should have been made. Nothing has, how- 

 ever, to my knowledge, been since published in connexion with the subject 

 neither in this country nor in Europe. M. D'Orbigny discovered in the Rio 

 Parana, South America, a very remarkable fresh water bivalve, which he named 



* Page 167 figs, a and b. 



