PLATE LUI— Continued. 



C(ELOSPiRA Camilla, H;ill. 



Figs. 24-26. Dorsal, iirotile ami ventral views of a typical specimen; showing' the contour and surface char- 

 acters. X 2. 



Fig. 27. The interior of the bra<-hial valve ; showing; the elevated anil somewhat recurveil hinge-plate. X 4. 



Pig. 28. The interior of ii pedicle valve; showing the open delthyriutn. the teeth anil muscular impres- 

 sions. X 4. 



Corniferous limestone. Caledonia, N. ¥. 



Fig. 29. The interior of a pedicle-valve ; showing characters similar to tliose of the preceding figure. X 2. 



Fig. 30. The exterior of a pedicle-valve. X 2. 



Fig. 31. The interior of a brachial valve ; showing the hinge-plate and median ridge. X 3. 

 Corniferous limestone. Lc Roy, N. Y. 



CffiLOSPIRA ACUTIPLICATA, Coiliud. 



Figs. 32-3."i. Doi'sal, profile, ventral and frontal views of the exteiior of a typical specimen ; .showing the 

 contour, coarse, sharp plication and concentric lineation of the v.alves 

 (/Orniferous limestone. Jamesville, N. Y. 

 Fig. 3ti. The interioi' of a portion of the bi-achial valve; showing the i-ccurved hinge-plate, ileej) ilental 



sockets and median I'idge. X 3- 

 Fig. 37. The exterior of a pedicle-valve slightly imperfect about the raaigins. X 2. 

 Fig. 38. The interior of the same specimen ; showing the open delthyrium and teeth. X 2. 



Corniferous limestone. JVate)-Io(i, N. Y. 

 Fig. 39. The interior of a brachial valve with faint lateral plications ; showing the hinge-plate, dental 

 sockets and median ridge. 



Corniferous limestone. Sangerfield, N. Y. 



Genus LEPTOCGELIA, Hall. 



Page 13ii. 



Leptoc(ELia flabellites, Hall. 



Figs. 40-42. Dorsal, ventral and profile views of an average example ; showing the contour and sui'face 

 characters. 



Fig. 43. The interior of a brachial valve ; showing the structui'e of the hinge-plate, dental sockets and 

 muscular area. 



Fig. 44. A profile of a large shell ; showing the plano-convex contour. 



Fig. 45. The interior of a brachial valve, somewhat imperfect about the margins ; showing a slight varia- 

 tion of the characters as represented in tig. 43. 



Fig. 46. The cardinal region of another brachial valve, enlarged ; showing the excavation of the cardinal 

 process im either side of a median ridge, and the projection of the crural lobes. X 2. 



Fig. 53. The interior of a pedicle-valve ; showing the open delthyrium, teeth, adductoi' and diductor scars. 

 Oriskany sandstone. Cumberland, Maryland. 



LEPTOCffiLIA FIMBRIATA, Htlll. 



Fig. 47. Dorsal view of the posterior poi-fion of the shell; showing the fimbria of spinules or testaceous 

 jirocesses extending fi-om between the cardinal margins. X 3. 



Fig. 48. A profile of a brachial valve; .showing the elevation of the cardinal process and crura. X 3. 



Fig. 49. Caidinal view of a brachial valve ; showing the elevation of the cardinal process, socket-walls 

 and crura, and the foreshortened cardinal spinides. 



Fig. 50. Dorsal view of conjoined valves ; showing the exterior characters and the cardinal spinules. X 3. 



Fig. 51. The interior of a brachial valve; showing the structure of the articulating apparatus, the char- 

 acter of the muscular area, and the mai-ginal spinules which are inserted upon this valve. X 2. 



Fig. 52. The interior of a pedicle-valve ; showing the foramen, teeth and muscular aiea. X 2. 



Figs. 54, 55. Interiors of pedicle-valves ; showing some variation in the retention of the .structural features. 

 X 2. 



Oriskany sandstime. Oumberland, Maryland. 



