HAMILTON GROUP. 
209 
Among the numerous corals, the following have been selected as presenting some of the 
more common forms. 
1 and 2. Cystiphyllum cylindricum. (Lonsdale in Silurian Researches, p. 691, pi. 16 his, 
f. 3, 3 a and 3 h.) —Cylindrical; straight or curved; externally very rugose and striated; 
internally wholly vesicular. 
Fig. 1 with Aulopora iubceformis attached; the same is figured with this coral attached, in 
Silurian Researches, from the Wenlock limestone. 
Fig. 2, a smaller specimen, with the bases of crinoidal columns attached. Of these, the one 
at a evidently fixed itself while the coral was standing in an upright position; the one at h, 
and an intermediate one, evidently began their growth after the coral was thrown down, as 
their direction is at right angles to its axis. 
Localities —Moscow ; York ; Eighteen-mile creek. 
3. Strombodes helianthoides? (Piiil. Palceozoic Fossils, p. 11, pi. 5, f. 13. Cyathophyl- 
lum helianthoidum, Goldfuss, pi. 20, f. 2). — Turbinate, straight or slightly curved near 
[Geol. 4th Dist.J 27 
