XoIcK Oil RirliiiKUiil ami Related Foii.sUs 53 



Fig. 3. Tri])teroccras ricliiiioiuloiisis. A, ventral side; B, 

 lateral view of inverted specimen, -showing location 

 of siphuncle, toward the lateral angle the septum 

 slojics from the dorsal toward the ventral side in a 

 direction away from the a})ical end of the specimen; 



C, weathered specimen, with indications of the 

 numnniloidnl fillings of tlie interior of the sij)huncle. 



D, a similar weathered specimen apparently shoA\ing 

 the exterior of the siphuncle. The exact structure of 

 the siphuncle has not been determined. White- 

 water member of the Richmond group, at Richmond, 

 Indiana. 



Fig. 4. Conchopeltis miseneri. A, cast of specimen with 

 approximate outline indicated, exact outline un- 

 known. A, A, anterior pair of . grooves limiting 

 anterior "lobe" in which strong radiating ribs are 

 absent. B, B, C, C, second and third pair of ribs 

 or plications. F, posterior, unpaired plication. 

 B, outline, on lateral view. Whitewater member of 

 Richmond group, at Richmond, Indiana. 

 All of the specimens on this plate were collected by John 



Misener. 



PLATE II 



Fig. 1, A, B, C. Dinorthis retrorsa, Salter. Pedicel valves; 

 A, B, two views of the type, from Bird's-hill, north 

 of Llandilo, in southern Wales. C, another valve 

 from the same locality. 



Fig. 1, D. Dinorthis inflata, Salter. Interior of pedicel 

 valve from the type locality: in the Coniston lime- 

 stone, at Coniston, in northern England. 



Fig. 1, F, G, H. Hebertella Llandiloensis, sp. nov. Brachial 

 valves. F, figured incorrectly by Salter as one of 

 the valves of Dinorthis retrorsa; G, H, other valves 

 from the same locality: Bird's-hill, north of Llandilo, 

 in southern Wales. E, another brachial valve from 



