PLATE XXXIX. 



(Figs. 1-3 coiiies; 4-0, 39-11 by K. P. Wiiitfikld; 10-14, 19-27. 29-31, 34-3ii, 42 by (i. U. .Simpson; 15-18, 28, 32, 33, 87, 



3S by E. Emmons.) 



Genus VERNEUILIA, gen. nov. 



I'liRe ,iS. 



Vekneuilia cheieopteryx, de Veiiieuil. 



Figs. 1-3. Tlii-ee views ; showing the slight asymmetry of the shell, and the Irisuluate surface of each 

 valve. (After pk Vernbuil.) 



Miihile Devonian. Paffrath, Oin-maiiy . 



Genus AMBOCCELIA, Hall. 



Page 54. 

 Sefe Plate 29. 



Amboccelia umbonata, Comad. 



S. Three views of an average example ; showing the great convexity of the pedicle-valve, its me- 

 dian groove, and the depressed-convex, marginally concave brachial valve. 



The interior of the pedicle-valve ; showing the elevated nmbo, the thickened, unsupported teeth 

 and the partial filling of the delthyrium. X 3. 



The interior of the brachial valve ; showing the low cardinal pi-ocess, elevated crural plates, and 

 the four adductor scai-s. X 3. 



A preparation, showing the volutions of the spiral coils. X 3. 

 Hamilton shales. Western Neio York. 



Amboc(elia planoconvexa, ShiuiKu-d. 

 Figs. 10-13. Views of a rather large example ; showing the general form and contour of the valves. 

 Fig. 14. Posterior view of the same specimen ; showing the cardinal areas, the imperfectly developed 

 deltidial plates and chilidium X 3. 



Coal Measures. Springfield, Illinuis. 

 Fig. 13. A small individual. 



Fig. 15. Enlargement of the surface of the same specimen ; showing the short spinules. X 5. 

 Coal Measures. Manhattan, Kajisas. 



AMBOt;<ELiA spinosa, sp. nov. 



Fig. 16. The exterior of a brachial valve. 



Fig. 17. An enlargement of the surface ; showing the narrow, elongate depressions which were probably 



the bases of superficial spines. X 6- 

 Fig. 18. Internal cast of the same specimen ; showing the impi-ession of the dental sockets and crural 



plates, and the faint adductor scars. 



Hamilton group. Livonia Salt Shaft, iV. Y. 



Genus METAPLASIA, gen. nov. 



Page .51;. 



Metai'Lasl\ pyxidata, Hall. 



Fig. 19. Interior of a brachial valve ; showing the articulating app.iratus, adductor scars and vascular 

 sinuses about the muscular area and over the marginal regions. X 2. 



Fig. 20. Posterior view of the same valve ; showing the width of the cai'dinal ai'ea, elevation of the cardi- 

 nal process and socket-walls, and the linguate extension of the median sinus on the anterior 

 margin. X 2. 



Fig. 21. Internal cast of the pedicle-valve ; showing the median fold, and the impressions of divergent, 

 probably vascidar sinuses extending forward from the pedicle-cavity. X 2. 



Fig. 22. Interior of a portion of the pedicle-valve ; showing the luiri-ow cardinal area, thickened teeth and 

 deep muscular scar. X 2. 



Oriskany sandstone. Cayuga, Ontario. 



Genus SPIllIFERINA, dOkbigny. 



Page 61. 

 See Plates 29, 315. 



Spiiuferina, sp. ? 

 Fig. 23. Interior of a portion of the brachial valve ; showing the articulating apparatus and the divergent 



musculai' ridges in the bottom of the valve. X 3. 

 Fig. 24. A portion of the interior of the pedicle-valve ; showing a highly developed delthyrial callosity 

 uniting the dental lamellre and supported by a median septum. X 2. 

 Chester limestone. Caldwell county, Kentucky. 



