E. B. Andrews—On the Alleghany Coal-field. 288 
on the subject have placed this group of islands in this latter 
portion. During the visit of the United States Coast Survey 
steamer Hassler, a number of specimens of corals, of which - 
the following is the list, were picked up on the beaches of sev- 
eral of the islands : 
Pavonia gigantea Verrill, James Island. 
Pavonia clivosa Verrill, Indefatigable Island. 
Pavonia, sp., James Island. 
Astropsammia Pedersenii Verrill. 
Pocillipora capitata Verrill, Jervis and Charles Islands. 
Porites, sp. 
lighter. The specimen is too much rolled for nearer determina- 
tion, The Porites is massive. also, and in the same condition. 
The species are all, or nearly all, identical with those found 
at Panama. They are mostly reef-builders, but here live prob- 
ably isolated sid at a certain depth, having never been ob- 
served tn situ. In individual growth they are fully equal to 
those from more favored localities, the rolled pieces of Pavonia 
measuring six or seven inches in diameter, thus indicating 
masses of considerable size originally. They are not confined 
to the northernmost islands of the group, where we should 
more naturally look for them, from the greater proximity to 
the warm current, but as the list shows, a Pocillipora was foun 
at Charles Island. one of the southernmost. The probabilit 
of fragments drifting from one island to the other is very small, 
owing to the considerable depth of water between them. 
Art. XXXIX.—A Comparison between the Ohio and West Vir- 
gina sides of the Alleghany Ooal-field; by E. B. ANDREWS. 
[Read before the American Association, at the meeting at Detroit.] 
In the study of the Alleghany coal-tield it is necessary to 
have Some well defined geological horizon to serve as a datum 
line with which to collate the various strata. Sometimes the 
