PLATE Xlc— Coiilinued. 



Triplegia Wenlockensis, Davidson. 



Fig. 22. A cast of the interior of the pedicle-valve ; showing- the cariliiial adductor and diductor mnscnlar 

 scar.s and the impressions of the dental lamella. 

 Weiilock limestone. England. 



Genus MIMULUS, Barrande. 



rage 272. 



MiMULUS Waldronensis, Miller and Dyer. 



Fig. 23. View from the brachial valve of a very yonng- individual. The shell is nearly symmetrical, and 



shows an open triangular delthyrium, ending in a circular apical foramen. X S. 

 Fig. 24. The opposite side of the same specimen. X 5. 



(From Memoirs N. Y. State Museum, Volume I, No. I, plate iii, tigs. 9, 9a.) 

 Fig. 2.^. Cardinal view of an adult individual, the type specimen. The cardinal area shows no trace of 



deltidium or foramen. X ■*• 

 Figs. 2G, 27, 28. Other views of the same specimen ; showing the peculiar a.symmetry of the shell. 

 Niagara group. Waldnm. Indiana. 



IMiMULUs coNTRARius, BaiTandc. 



Fig. 29. The exterior of the pedicle-valve ; showing the broad median sinus. 



Fig. 30. Cardinal view ; showing the relative contour of the valves and the faint trace of the deltidium. 

 Etage Ei. Tetiii, Bohemia. 

 (After Barrandk, Systeme Silurien, Vol. V. pi. 9, tig. vi. A, E.) 



MiMDLus perversus, Barrande. 



Fig. 31. Dorsal view of the shell ; showing the sinus on the brachial valve and the uninterrupted cardinal 



area of the pedicle-valve. 

 Fig. 32. Cardinal view of the same specimen. 



Etage Ej. Listice, Bohemia. 

 (After Barra.nde, Systeme Silurien, Vol. V, pi. 1. tig. iii, c, B.) 



Genus STREPTIS, Davidson. 



Page 274. 



Streptis Grayi, Davidson. 



Fig. 33. View of a brachial valve which retains the lamellar expansion at one of the growth-lines. X 4. 

 Etage Eo. Lodeiiitz, Bohemia. 



(After Barrande, Systeme Silurien, pi. 83, fig. ii, 3a.) 

 Figs. 34. S.'). Brachial and anterior views ; showing the asymmetry of the valves, the concentric ornamenta- 

 tion and the perforated deltidium. X 5. 

 Fig. 36. Cardinal view of a similar specimen. X 4. 



Fig. 37. The cardinal process, broken at its tip, probably near the point of bifurcation. 

 Figs. 38, 39. Interiors of pedicle and brachial valves. 



Weulock limestone. Dudley, England. 

 (After Davidson, British Silurian Bi-achiopoda. pi. xiii. tigs. 15a, 176. 16b, 21, 19. 20.) 



