﻿342 DROMUS 



of bir.allcr knobs at the median line ; epidermis shining", tawny, 

 or greenish -yellow with two patterns of broken rays. One of 

 these consists of several contiguous, narrow rays composed of 

 dots or broken lines ; these alternate with wide rays, made of 

 peculiar blotches and fleckings of green ; hinge plate wide and 

 rlat ; left valve with two low, rough pseudocardinals, the hinder 

 larger, and two short, remote laterals ; right valve with three 

 l>seudocardina,ls, the middle one much the largest, and one di- 

 vided lateral; beak cavities deep, compressed; muscle scars 

 very small, impressed, the anterior ones rough ; pallial line 

 distant from the border in front ; nacre white or buff, some- 

 times salmon-red behind, thickened in front. 



Length 70, height 60, diam. 40 mm. 



Length 80, height 67, diam. 40 mm. 



Tennessee and Cumberland River systems. 



Type locality, Ilarpeth River; Cumberland River, Nashville, 

 Tenn. 

 Unio dromas Le.\, Tr. Am. Phil. Soc, V, 1834, p. 70, pi. x, 



fig. 29; Obs., L 1834, p. 182, pi. X, fig. 29. — CoNR.VD, Monog., 



X, 1838, p. 84, pi. xLvi, fig. 2. — Hanley, Biv. Shells, 1843, 



p. 181, pi. XXIII, fig. 25. — KusTER, Conch. Cab. Unio, 1861, 



p. 172, pi. Liii, figs. 3, 4. — Reeve, Conch. Icon., XV'L 1864, 



pi. vni, fig. 29. 

 Margarita (Unio) dromas Lea, Syn., 1836, p. 16 ; 1838, p. 16. 

 Cyprogenia dromas Agassiz, Arch, fiir Xaturg., L 1850, p. 48. 

 Margaron (Unio) dromas Lea, Syn., 1852, p. 23; 1870, p. 34. 

 Dromiis dromiis Simpson, Syn, 1900. p. 615. 

 Droiinis dromas Ortmanx, Ann. Car. Alus.. X'TIT, i()i2, p. 



315, fig. 18. 



A peculiar Naiad both in the character of the shell and mar- 

 supium. The pattern of coloring in fine specimens is one of the 

 most beautiful among the L'nionida'. The shell characters 

 would seem to ally it rather closely to Cyprogenia, but the mar- 

 supium is totally different from what it is in that group, con- 

 sisting of a fringe of short, distinct ovisacs bordering the 

 entire outer gills, while in Cyprogenia it consists of a few 



