DEVONIAN SPECIES. 35 



MOLLUSOA. 

 BEACHIOPODA. 



STROPHOMENID^. 



Genus HEMIPEONITES, Pander. 

 Hemipeonites CHEMUNaENSis var. ARCTOSTEiATA, Conrad (sp.). 



• Plate 3, fig. 2. 



Strophomena Chemungensis, Conrad (1843), Jour, Acad. Nat. Sci. Philad., VIII, 257, pi. 



14, fig. 12. 

 Orthisina arctostriata, Hall (1861), Thirteenth Eeport Regents Univ. N. Y. on State 



Cab. N. H., 80 ; and (1862) Fifteenth do., 185 and 186, figs. 1 and 2. 

 Streptorhynchus arctostriatus, Hall (1863), Sixteenth Eeport Eegents Univ. N. T. on 



State Cab. N. H., 62. 

 Streptorhynchus Chemungensis var. arctostriata, Hall (1867), Palseont. N. T., IV, 71.* 



Shell small, nearly semicircular, rather depressed ; hinge very nearly 

 or quite equaling the greatest breadth; lateral extremities about rectangular; 

 anterior and lateral margins forming together a semicircular curve. Ven- 

 tral valve most convex at the beak, which is only moderately prominent, 

 and a little distorted, but not arched, and seems in the figured specimen to 

 have been broken at the apex in becoming detached from some body to 

 which it had grown ; area comparatively low, nearly flat, and very slightly 

 inclined forward, or ranging nearly at right angles to the plane of the valves ; 

 pseudo-deltidium triangular and a little convex ; surface marked by small 

 radiating strise. Dorsal valve unknown. 



Length, 0.31 inch; breadth, 0.45 inch; convexity of ventral valve, 0.12 

 inch. 



So far as can be determined from a single specimen of a ventral valve, 



* Professor Hall's latest conclusion on this point is, that Conrad's Strophomena 

 Chemungensis, published in 1843, includes, either as varieties or individual modifica- 

 tions of form, etc., all of the following proposed species, viz., Strophomena bifurcata, 

 Hall, 1843; S. arctostriata, Hall, 1843; S. peetinacea, Hall, 1843; Orthis perversa, Hall, 

 1847; Orthisina arctostriata, Hall, 1860; 0. alternata. Hall, 1860; and Orthis inequalis 

 and 0. parvis, Hall, 185S ; as well as Streptorhynchus pandora, Billings, 1860. The 

 names S. pandora, S. arctostriata, S. perversa, and 8. pectinacea, he retains for varie- 

 ties of Mr. Conrad's species (see Palaeont. N. Y., IV, 67-73). 



