86 WOODWARD : ON A CARBONIFEROUS TRILOBITE. 
from Bishopston, and according to the latest information received 
their geological horizon is practically the same. 
The following points of difference may, however, be ob- 
served, viz., (1) The greater breadth of G. Barkei in proportion 
to its length ; (2) the slightly greater length of the cheek-spines 
in the Nidderdale specimen ; and (3) the rather broader axis 
to the body segments ; and, again, (4) the more strongly-marked 
ribbing of the coalesced segments of the pygidium, which is also 
slightly more pointed than is the tail of G. Barkei ; (5) the 
cervical segment is more strongly marked in the Yorkshire 
specimen ; (6) the apparent greater size of the eyes in this 
specimen is really deceptive, and is caused by the head being 
rather flattened out and compressed. On the whole, however, 
these two forms approach very closely to each other, and, seeing 
they are pronounced by Dr. Wheelton Hind to occur on the 
same geological horizon, there is strong presumptive evidence 
in favour of their specific identity. 
I prefer then to refer Mr. Hawkesworth's Trilobite to 
Grifpthides Barkei, not feeling justified (in the present state 
of our knowledge) in the establishment of a new species. 
