SYNOPSIS OF THE CYPMNIDyE OF PENNSYLVANIA. 



391 



CHROSOMUS ERYTHROG ASTER, Raf. 

 L. c, Agassiz, 1. c, Cope, Proc. A. N. S. Phila., 1864, 281. 



Outline from muzzle to dorsal fin gently arched and compressed, then rather suddenly 

 descending to the elongate caudal peduncle; ventral outline nearly straight. Head slightly 

 elongate, contained in length to base of caudal four and one-fifth times; operculum longer 

 than high, rounded right-angled posteriorly; muzzle not quite equal an eye's diameter; 

 latter 3.25 to .50 in length of head. 



oeales small 34 — 5 to 80 — 85, concentric lines strongest, their edges on the belly so thin 

 as tb transmit the form of the base of the scale below, giving the appearance of a reversed imbrication. Lateral 

 line extending on about 32 scales. Base of dorsal fin two-thirds its height; latter two and two-thirds times in 

 length from first ray to base caudal ; base of anal slightly longer than that of dorsal, equal depth of caudal pedun- 

 cle at middle. Hays D. 1. 8, C. 1.9, A. 1. 9-8. P. 18, the rays on £ thickened, form rounded, not attaining 

 vcntrals; latter just reaching vent. 



Total length 2.375 in.; end muzzle to first dorsal ray 1.00 in.; latter to origin caudal .975 in.; greatest depth 

 at ventrals .445 in. 



Above bright chestnut with a blackish vertebral line, margined below by a blackish band from the superior 

 opercular angle straight to the upper side of the caudal peduncle ; a broader black band from end of muzzle to 

 middle caudal peduncle, deeurved on side, and separated by a broad silver band from the superior; below this 

 silvery. Both the belly and the band are in spring and summer brilliant crimson. 



Specimens of this species from Illinois exhibit a more obtuse, founded muzzle ; one 

 from the White River, Indiana, exhibits a straight muzzle, while several from Macomb 

 County, Michigan, from waters flowing into Lake St. Clair, have a shorter muzzle, not at 

 all deeurved. The latter have also not a trace of lateral line, which is present in all the 

 rest. 



In Pennsylvania this species occurs in the Mahoning and other tributaries of the Alle- 

 ghany. It is not exceeded by any of the family in brilliancy of color or gracefulness of 

 form, and is often seen in aquaria. 



CHROSOMUS EOS, Cope. 



Proc. Acad. Nat. Sci. Phila., 1861, 523. 



Another small and pretty species, representing the last in the water basin of the Sus- 

 quehanna. The number of teeth 5-5, is unusual among our species. 



Mouth small, not extending so far as opposite nares, chin slightly projecting; eye a little over throe times in 

 length of head, one-fifth less than interorbital width. Temporal width equal from occiput to opposite anterior 

 margin pupil. Greatest depth five and one-third times from end muzzle to origin of caudal fin, head four times 



