| Geology. 417 
: oma by the nucleus at the surface of the shell were adduced the 
: sity of the fluid strata’ were due to the pressures they su nd i 
| a. of the nucleus which prod e great pressure against 
: oy than by the collapse and subsidences of the latter. The direction of 
forees which would tend to produce a rupture from the purely eleva- 
sO a 
would not be resisted in the same manner. 
4. On the Great Pterygotus (Seraphim) of Scotland, and other Species ; 
by Mr. J. W. Saxrsr, (Proc. Brit : 
This paper i m 
Quarterly Geological Journal for 1855, describing some new and large 
t Silurian rocks of the south of Scot- 
land, ‘They were described under the name of Himanthopterus, and 
Were supposed to differ from the published fragments of the great Ptery- 
In the general 
«ts and tail, in the want of 
n th 
appendages to the abdomen, as we 
swimming feet, mandibles, maxill 
. 0n further examination the closest#rese 
eyes, as represented by 
tical, and the group, as 
small and moderate-sized 
than any living species, 
f six or eight feet! The collec- 
