PLATE LIX. 



(Figs. 1 12, 18-22, 26, 30, 31, 37, 38 by II. V. WuiTFiELD; 13, U, 24, 25, 28, 29, 32, 33 by E. Emhons; 15-17, 23, 27, 3»-3« 



by G. B. Simpson.) 



Genus LIORHYNCHUS, Hall. 



Page 193. 

 LlORIIYNCHUS LIMITARIS, VillUIXL'lll. 

 Fifjs. I, 2. Dorsal and frontal view8 of a small individual. 



Marcellus shales (Goniatile limestone). iS<:Ju>harie cnunty, N. Y. 

 Figs. 3-5. Frontal, cardinal and ventral views of a larg-er specimen. 

 Limestone of the Mai'celhis shales. Avon, N. Y. 



LlOUHYNCIIUS DUBIUS, Hall. 

 Figa. 6, 7. Ventral and dorsal views of a typical specimen. 

 Marcellus shales. Locality f 



LxORHYiNCHUS MULTICOSTA, Hall. 

 Fig. 8. The exterior of a pedicle-valve of an elongate specimen, the regulai- growth of which haa been 



interrupted in the umbonal region. 

 Fig. 9. The brachial valve of a more orbicular and typical shell. 

 Fig. 10. A cardinal view ; showing the convexity of the Ivalves. 

 Hamilton group. Western New York. 



IjIORHVNCHI'.S ME.SACOSTALI.S, Hall. 

 Fig. 11. The exterior of the pedicle-valve ; showing the inequal plication of the sinus. 

 Fig. 12. An internal cast of a large brachial valve; showing the position of the median septum, the elon- 

 gate muscular scars and the absence of plications on the latei'al slopes. 

 Chemung group. Tompk'nis county, N. Y. 



LlORHYNGHUS LaURA, Blllillgb. 

 Figs. 13, 14. Ventral and dorsal views of a rather elongate individual. 

 Fig. 15. Posterior view of the hinge-plate and crura ; showing the great elevation of the latter and their 



basal expansions. X 4. 

 Fig. 16. The same specimen, viewed from above ; showing the narrow, submarginal dental sockets, the 



broad triangular divisions of the hinge-plate, the median septum and the recurvature of the 



long crura. X 4. 

 Fig. 17. The interior of the umbonal portion of the pedicle-valve ; showing the open delthyrium, small 



teeth and faint muscular impression. 



Hamilton group. Widder, Ontario. 



LiORHYNCHDS Kelloggi, Hall. 



Fig. 18. Cardinal view of an internal cast ; showing the cavities left by the dental plates, median septum 



and crura. 

 Figs. 19, 20. Dorsal and vential views of a normal adult ; showing the obsolescence of plications except 



upon fold and sinus. 



Hamilton group. No^ihem Ohio. 



LlORHYNGHUS QUADRICO.STATUS, VailUXeill. 

 Fig. 21. View of a crushed and somewhat distorted pedicle-valve of large size ; showing the character of 



the plication. 

 Fig. 22. A small internal cast of the bi-achial valve in which the lateral jilications are obsolete. 



