NATURAL SCIENCES OP PHILADELPHIA. 87 



aa. Distance from pectoral to ventral equal to or greater than 

 from ventral to anal. 

 Operculum higher than long. From ventral to anal four 

 times from muzzle to lower origin of caudal ; head two 

 and three-fourths times in length to same point : 434 

 rows of scales in ring: 57 in lateral line: faint traces of 



radii on a few anterior rows. One spec longirostris. 



Operculum- longer than high. Scales smooth, in 41 rows 

 in ring behind ventrals ; lat. lin. 613. Head three and 

 one-sixth in length to inferior base of caudal. Eye one 

 and two-thirds in frontal breadth. Generally as in h u r o- 



nensis. Three spec otarius. 



II. Horizontal diam. of eye contained ir-ore than twice, 

 from its post. bord. to operculum. 



a. Scales smooth. 



Eye 2 in front; lat. line 58 ; pect. fin 13 rays sp. from Texa3. 



Eye 3^ in front ; lat. line 64 ; pect. fin 11 rays. One spec, oxyurus. 

 aa. Scales on anterior half or more of body crenate and some- 

 what radiate and tuberculate. 

 Head three times from end of muzzle to lower origin of cau- 

 dal ; from ventral to pectoral a little less than from v. to 

 anal. Opercular anterior suture longer than length of 

 operculum. Eye three and two-thirds to three and five- 

 sixths in frontal breadth. Scales 47 to 50 in ring behind 

 ventrals, and 56 in lateral line. Two specimens osseus. 



In the L. otarius the temporal breadth is contained more than five times 

 in the total length of the head. D. 8, A. 9, P. 12. The borders of the scales 

 are hirsute, as in h u r o n e n 9 i s, and the shorter straight, behind the line of 

 the ventral fins, except a few toward the dorsal region. The first row in front 

 of the dorsal is the third from the inferior origin of the caudal, and fifth from 

 the anal. The parietal membrane shields present each a principal angle ante- 

 riorly near the median line ; five scales bound the occipitals posteriorly. From 

 end of muzzle to anterior border of orbit 5 in., 6 lin. ; to anterior horder of 

 operculum 7 in., 10 lin. ; to posterior edge of do., 8 in., 8 lin. ; to origin of 

 ventrals, 15 in. ; to inferior origin of caudal, 24 in., 9 lin. Lead-colored 

 above ; the sides silvery ; below white. Pectoral and ventral fins unspotted ; 

 the others spotted : the anal sparsely ; a black spot at base of caudal. 



Number of species obtained by Dr. Hammond, 23 ; in the Michigan synop- 

 sis, 63 ; species occurring in both, Amia, Hyodon, Stizostedium americanum, 

 Ceratichthys, Pimephales promelas, and Semotilus corporalis. In the 

 following list is shown the number of species of the synopsis as yet known 

 to occur in the Ohio and tributaries, the Susquehanna, and the Delaware : 



Michigan. Ohio. Susquehanna. Delaware. 



Ganoidei 3 2 



Nematognathi .. 4* 3 1 1 



Eventoguathi 28 10 6 4 



Malacopterygii * 7 ?3 1 1 



Acanthopterygii 19 12 ?5 ?3 



Supplementary Note on a peculiar genus of CrpRiNiDiE. 



I obtained a small fish in the Kiskiminitas River, Western Pennsylvania, 

 the present spring, which appears to be related in structure to allied genera 

 of the Cyprinidae, as Acerina is to some others among Percidse. Its gene- 



* Ameurus d e k a y i must be added to the Catalogue pt. I., and the supposed Ictalurus gra- 

 cilis is the coerulescens. 



1865.] 



