PLATE XVB—Continued. 
Strophalosia radicans, Winchell. 
27. A pedicle-valve, attached by its entire outer surface and spines to a Fistulipora. X 2. 
28. A pedicle-valve, situated in a cavity among- the polypites of Acervularia Davidsoni. There is a slight 
attachment by the apex of the valve, but fixation is mainly effected by the spines, those on the 
cardinal margin creeping along the surface of a polypite, and several 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 fine concentric annulations. X 3. 
29. The calyx of a single polypite of Acervularia Davidsoni, to which is attached a pedicle-valve of 
this species ; its adherent spines running between the septa of the coral. X 3. 
30. An attached specimen, 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, figs. 29, 30.) 
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. Gonewango, N. Y. 
Strophalosia scintilla, Beecher. 
32. A specimen retaining both valves, attached to the surface of Spirifer Marionensis. This specimen 
shows no trace of spines. X 6. 
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 6. 
34. The interior of a pedicle-valve attached to the surface of Syringothyris Hannibalensis; showing the 
few short spines which characterize the species. X 4. 
Choteau limestone. Pike county, Missouri.“ 
Strophalosia, sp. ? 
35. A very small specimen attached to Spirifer Marionensis. This specimen is peculiar in showing 
spines on the surface of the brachial valve. It occurs in association with S. scintilla, and it 
may possibly prove the young of that species. X 8. 
Strophalosia Cornelliana, Derby. 
36. Posterior portion of the interior of the pedicle-valve ; showing the area, deltidium, teeth and mus¬ 
cular scars. X 3. 
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. Bomjardim, Brazil. 
