PLATE XX. 
Clathropora alcicornis Hall. (Page 56.) 
Fig. 1. A view of the type specimen, natural size. 
2. 3. Enlarged views of the surface of the same. 
4. A tangential section of the type specimen, X 30, showing Its generic identit; 
with Clathropora. 
Rochester shale, Lockport, X. V. 
Clathropora frondosa Hall and var. intermedia Nicholson and Hinde. (Page 56.) 
[See also PI. XXI, Bgs. 6,7.] 
5. A view of the type specimen of the snail fenestrulcd form, which Nicholsoi 
and Hinde apparent ly consider •(! as typical ( '. frondosa. 
6. Natural-sized view of another of Hall's type specimens, later distinguished b; 
Nicholson and Hinde as var. intermedia. 
7, 8. Enlarged view of the surface, showing the zocecial characters in both species aw 
variety . 
!). 10, 11. Three fragments of zoaria, showing the pointed basal extremity 
Rochester- shale, Lockport , N. Y . 
Figs. 1,2, 3, 5, 6,7, 8 are after Hall, Natural History of New York, Paleontology 11,1852 
104 
