PLATE LU-Contlauecl. 



LlORHVNOHUS GLOBDLIFOKMIS, VailUXeiU. 

 Vlg. 38. The exterior of the brachial valve ; showing its rotundity, the low, faintly plicated fold and smooth 

 convex lateral slopes. 



Hamilton group. Otsego county, N. Y. 

 Vig. 34. The exterior of a peiiicle-valve with traces of marginal plications on the sinus. 

 Pig. 35. An internal cast of a more orbicular shell with stronger median plication. 



Black shale (Genesee shales). Lexington, Indiana. 

 Fig. 3(5. An internal cast of the brachial valve ; showing the extent of the median septum and the form of 



the adductor scara. 

 Fig. 37. Enlargement of the umbonal portion of an internal cast of the brachial valve ; showing the filling 

 of the dental sockets aud spondylium, the cavities left by the removal of the hinge-plate and 

 thickened median septum. 



Chemung ()) group. Bromne county, N. Y. 



LlORHVNCHUS CASTANEUS, Meek. 

 Figs. 38, 39. Profile and doi-sal views of a well preserved individual ; showing the great convexity of the 

 brachial valve, and the exceedingly obscure plication visible only on the median fold. 

 Lower Devonian. Eureka District, Nevada. 



LlORHYNCHUS ROBU8TU8, sp. 110 V. 

 Figs. 30, 31. Cardinal and ventral views of a very sharply marked internal cast of large size, representing 

 an hitherto undescribed species j showing the muscular impressions of both valves and the 

 vascular sinuses in the pedicle-valve radiating from the impression left by an umbonal testace- 

 ous callosity. 



Chemung gi-oup. Steuben county, N. T. 



LiORHYNOHUs Kelloqgi, Hall. 



Figs. 33, 33. Dorsal and ventral views of an adult shell with more distinct plication than that i-epresented 

 in figures 19, 20. 



Hamilton group. Northern Ohio. 



LlORHYNCHUS LeSLEYI, sp. IIOV. 

 Figs. 34-36. Dorsal, ventral and pi-otile views of a mature shell ; showing the I'ather obscurely defined fold 

 on the convex^brachial valves, the deep sinus of the j>edicle-valve, and the unusually complete 

 plication of the lateral slopes. 



Upper Devonian. Pennsylvania. 



LlORHYNCHUS Newbekryi, Hall and Wliitfieid. 

 Fig. 37. An internal cast of the brachial valve ; showing the large size of the shell, low median fold, and 



fine plication. 

 Vig. 88. Cardinal view of an incomplete internal cast of both valves. 

 Upper Devonian. KelloggsviUe, Ohio. 



