NATURAL SCIENCES OF PHILADELPHIA. 523 



is L. cataractusof Prof. Baird,* an abundant fish, and one that takes the 

 bait very eagerly. That inhabiting the Brandywine, the Rancocas and other 

 tributaries of the Delaware, differed from this and from the New England 

 species, L. p u 1 c h e 1 1 u s, Storer, in the greater size of its scales. The num- 

 ber which the lateral line traverses is 47 ; in c a t a r a c t u s, the same; in 

 p u 1 c h e 11 u s, 59. Other specific peculiarities were presented in the follow- 

 ing diagnostic form : 



Length of head entering into total length (including caudal fin), four and 

 three-quarter times ; greatest depth of body seven-eighths the length of the 

 head, of which the diameter of the orbit occupies a little more than one-fifth. 

 Length of the superior surface of the head a little less than one-third the 

 distance between the extremity of the muzzle and the base of the dorsal fin, 

 and twice the breadth between the orbits. The distance from the base of the 

 caudal fin to the anterior border of that of the dorsal is nine-tenths the dis- 

 tance anterior to the latter point. Ventral fin opposite the dorsal ; its ante- 

 rior border shorter than that of the anal, which is similarly related to the 

 dorsal in that respect. The muzzle projects slightly beyond the mandible. 

 Mouth cleft obliquely downward, its rictus corresponding with a point mark- 

 ing three-fourths the distance from the end of the muzzle to the anterior rim 

 of the orbit. Barbels quite small, even in large specimens. Membranous 

 border of the operculum narrow ; that at the bases of the scales slight. The 

 exposed portious of the scales upon the sides are twice as high as wide, and 

 nearly symmetrical ; there are about twenty strong radii, and numerous 

 weak concentric lines, which are strongest near the margin. Eight rows 

 above the lateral line, five below ; total fourteen ; seven rows upon the caudal 

 peduncle at its middle. 



This species had been called Semotilus corporalis by Mr. Abbott, (Proceed. 

 Acad. Nat. Sci., Phila., 1861, p. 154,) but Mr. Cope was of the opinion that 

 Cyprinus corporalis of Mitchell was a different fish. He also dissented from 

 the generic determination of the former author. He proposed, therefore, that 

 it be known as Leucosomus rhotheus. Mr. Abbott's radial formulae were 

 correct, but there were apparent inaccuracies in the description of color ; with- 

 out living specimens, a correction could not be made, but its general appear- 

 ance when drawn from the water, as far as Mr. Cope recollected, was silvery, 

 without spots or bands. Shortly after death the upper regions became of a 

 light steel blue. Mr. Cope further stated that Semotilus alromaculatus of Mr. 

 Abbott's article was also a Leucosomus. Specimens of another Leucosomus 

 had been sent to the Academy from the Alleghany River. 



He had found neither Ceratichthys nor Exoglossum in the Delaware streams, 

 though they abounded in those of the Susquehanna. 



Mr. Cope stated that he had made the interesting discovery of the occur- 

 rence of the genus Chrosomus Raf. in the Susquehanna basin. It had been 

 previously known exclusively as a transalleghenian type. The specimens 

 of the species which he called Chrosomus e o s, were caught in the Meshoppen 

 creek, Susquehanna county. The peculiarities which first strike the eye as 

 separating them from those of C. e ry th r og as t er, are 1st, the absence of 

 lateral line ; 2d, the nearly straight dorsal outline; 3d, the want of prominenee 

 of the premaxillary region, and the downward slope of the mouth ; 4th, the con- 

 fluence on the tail of the lateral colored bands. A groove extends on each side 

 of the body above the position corresponding to that of the rudimentary lateral 

 line of ery t h rogaste r ; along this the superior lateral black stripe runs. 

 The inferior band becoming confluent with the upper, traverses the median 

 lateral line of the peduncle of the tail. The depth of the body anterior to the 

 dorsal fin enters the length exclusive of the caudal fin, a little more than four 

 times. Thus it is a more slender species than the e ry thro gas t e r. The 



* Iconoar. Encyclop. ii. p. 216. 



1861.] 



