PLATE XVb— Continued. 



Steophalosia radicans, Wiuclu'll. 



Fig. 27. A pedicle-valve, attached by its entire outer surface and spines to a FiSTCLipunA. X 2. 



Fig. 28. A pedicle-valve, situated in a cavity among the polypites of ^ce?-i)uiana X)ai)irfso7n. There is a slight 

 attachment by the upex of the valve, but tixation is mainly i-ffected liy the spines, those on the 

 cardiniil margin ci-eeping along the surface of a polypile, and sevei-al of those which are on the 

 body of the valve crossing the cavity, their extremities being somewhat obscured by the matrix 

 of the specimen. These latter spines appear to increase slightly in diameter from the surface 

 of the shell outward, and their surface is marked with tine concentric annulations. X 3. 



Fig. 29. The calyx of a single jiolypite of AcenniJaria Davidsoni, to which is attached a pedicle-valve of 

 this species ; its adherent spines running between the septa of the coral. X 3. 



Fig. 30. An attached specuraeii, which retains the concave brachial valve in position, and shows the cardinal 

 areas and deltidia of both valves. X 3. 



Hamilton group. Little Traverse Bay, Michigan. 



Strophalosia hystricula, Hall. 



(See Plate XVII, Hgs. 29, 30.) 

 Fig. 31. An internal cast of a pedicle-valve, which shows the scar of attachment and impressions of the 

 bases of spines over the body of the shell. X 3. 

 Chemung group. Coneioango, N. Y. 



Strophalosia scintilla, Beecher. 



Fig. 32. A specimen I'etaining both valves, attached to tlie surface of Spirifer Marionensis. This specimen 



shows no trace of spines. X 6. 

 Fig. 33. Another specimen which retains both valves, attached to a brachial valve of Productella pyxidata. 



The spines about the margin should have been represented as belonging to the lower, not to 



the upper (brachial) valve. X (5. 

 Fig. 34. The interior of a pedicle-valve attached to the surface of SyHngothyris Hannibale7isis ; showing the 



few short spines which characterize the species. X 4. 

 Choteau limestone. Pike county. Missouri.' 



Strophalosia, sp. ? 



Fig. 8."). A Very small specimen attached to Spiriftr Marioiie>usL<i. This specimen is peculiar in showing 

 spines on thi' surface of the brachial valve. It oc:curs in association with iS. .':cintiUa, and it 

 may jiossilily prove the young of that species. X 8- 



Strophalosia Cornelliana, Derby. 



Fig. 36. Posterior p, ition of the intej-ior of the pedicle-valve ; showing the aiea, deltidiuni, teeth and mus- 

 cular scars. X 3. 



Fig. 37. The interior of an imperfect brachial valve which retains the cardinal process, and shows the 

 muscular scars and brachial impressions. X 3. 

 Coal Measures. Bmnjardim, Brazil. 



