1856.] 



203 



scription and a figure of this species, we refer to Storer^s " History of the Fishes 

 of Massachussetts," in the fifth volume of the memoirs of the American 

 Academy. 



2. LuxiLUS coMPRESSus. RutUus compressus, Eafin. Ichth. Ohiens. 1820,51. 

 KiiiTL. Rep. 169. Leucisciis compressus, Kirtl. Bost. Journ. of Nat. Hist. iv. 

 1843, 306. PI. XT. fig. 2. Storer, Synops. 1846, 157. 



3. LuxiLUS OBESUS. Leuciseus ohesus, Storer, Proc. Bost. Soc Nat. Hist, 

 i. 1845, 48 ; and Synops. 1846, 166. Stilbe ohesus, Agass. Amer. Journ. of Sc. 

 2d. Ser. xviii. 1854, 359. 



4. LuxiLTJS occiDENTALis. Leucosomus occidentalism B. & G. Proc. Acad. Nat. 

 Sc. Philada. vii. 1854, 137. 



5. LuxiLUS LEPTOSOMUS. Outline regularly subfusiform ; the depth forming a 

 little more than the fifth of the entire length. The head enters five times 

 and a half in the same dimension. The anal fin is a great deal larger than 

 the dorsal. The scales are larger than in any other species of the same 

 genus. 



D 9 ; A 13+2 ; C 5, 1, 9, 8, 1, 5 ; V 9 ; P 15. 



Color greyish brown above ; light reddish beneath ; sides silvery. Forked 

 margin of caudal, blackish grey. 



From Dry Creek, near Victoria, Texas ; collected by Dr. C. B. Kennerly, un- 

 der Major W. H. Emory, TJ. S. A., Commissioner U. S. and Mex. Boundary. 



G. LuxiLUS SECo. Body deeper than in L. leptosomiis ; depth equal to the 

 fourth of total length. Head contained five times and a half in the same dimen- 

 sion. Eye very large ; its diameter entering three times only in the length of 

 the side of the head. Mouth small. Scales of moderate development. Light 

 brown above, yellowish white beneath ; sides silvery. 



Specimens of this species were collected in the Rio Seco, a tribunary of the 

 Rio Nueces, Texas, by Dr. C. B. Kennerly, under Lieut. A. W. Whipple, U. S. A. 



7. LuxiLUS LuciDus. General form resembling that of L. seco. The head, 

 however, is contained but four times in the length of the side of the head. 

 The mouth is a good deal larger, whilst the eye is smaller. The scales, like- 

 wise, attain to a greater development. The color is the same as in the preceding 

 species, with the exception that the tint of the back has a greyish hue and 

 extends more to the sides. 



Collected by H. B. MoUhausen, under Lieut. A. W. Whipple, TJ. S. A., in 

 Coal Creek, a tributary of the South Fork of the Canadian River, and also 

 twenty miles west of Choctaw Agency. 



In the Ichthyologia ohiensis we find the genus 



Semotilus, Rafin. 



which, though imperfectly characterised, leaves not doubt as to the species the 

 author intended to include in it. Semotilus dorsalis and Semotilus ccphalus, are 

 both well known species. S. diplemia, on the other hand, does not come under 

 this head. The genus Semotilus we therefore restore with the following charac- 

 ters : Head subconical, both jaws equal or else even anteriorly ; cleft of mouth 

 slightly oblique upwards. The mouth itself being large, surmounted with soft 

 lips and without barbels. The isthmus is rather narrow. The insertion of the 

 ventral fins is situated in advance of the anterior margin of the dorsal fin which 

 is higher than long. The caudal is bifurcated. The scales, of moderate size. 

 The pharyngeal bones are narrow, very slightly expanded upon the upper half 

 of their curve. The teeth are of the voratorial kind, of the hooked type with- 

 out grinding surface, stoutish, moderately hooked and disposed upon a double 

 row in the following manner: 2 | 5 5 | 2; sometimes 2 | 4 5 | 2. Generally 

 speaking, a black or brown spot may be observed at the base of the anterior 

 margin of the dorsal fin. 



