I'LATE LIX— Continueil. 



LlORHYNCHUS (iLOUULIFOKMLS, VaiUiXCIU. 

 Fig. 23. The exterior of the brachial valve ; .showing its rotundity, the low, faintly plicated fold and smooth 

 convex lateral slopes. 



Hamilton groiijj. Otsego amnty, N. Y. 

 Fig. 24. The extei-ior of a pedicle-valve with traces of marginal plications on the sinus. 

 Fig. 25. An internal cast of a more orbicidar shell with stronger median plication. 



Black shale (Genesee shales). Lexington, Indiana. 

 Fig. 26. An internal cast of the bi-achial valve ; showing the extent of the median septum and the form of 



the adductor scai-s. 

 Fig. 27. Enlargement of the umbonal portion of an intei-nal cast of the brachial valve ; showing the tilling 

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

 thickened median septum. 



Chemung (?) group. Broome county, N. Y. 



LlORHYNCHUS CASTANEus, Meek. 

 Figs. 28, 29. ProHle and dorsal 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 ROBUSTUS, Sp. IIOV. 

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

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

 vascular sinuses in the i)edicle-valve radiating from the impression left by an umbonal testace- 

 ous callosity. 



Chemung group. Steuben county. N. Y. 



LlORHYNCHUS KeLLOGGI, Hilll. 

 Figs. 32, 33. Dorsal and ventral views of an adult shell with more distinct plication than that represented 

 in figures 19, 20. 



Hamilton group. Northern Ohio. 



LlORHYNCHUS LeSLEYI, S[i. IIOV. 

 Figs. 34-36. Dorsal, ventral and profile views of a mature shell ; showing the rathei' obscurely defined fold 

 on the convex Virachial valves, the deep sinus of the pedicle-valve, and the unusually complete 

 plication of the lateral slopes. 



Upper Devonian. Peniisylvania. 



LlORHYNCHUS Newbehryi, Hflll aiul Whitlield. 

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



tine plication. 

 Fig. 38. Cardinal view of an incomplete internal cast of both valves. 

 Upper Devonian. Kelloggsinlle, Ohio. 



