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forming a judgment from external appearances only; 
There are I find many species that might be taken for 
varieties., as they gradually pass through different degrees 
of obliquity* This appears to be the species Mr. Parkinson 
thinks might, if not otherwise designated, be called glabra; 
1 am afraid however that there are still more glabrous ones 
to abtain the title. The line of the hinge is, as he observes* 
finely crenulated, as well as three transverse teeth which 
terminate the hinge at each end s so are some of the other 
species of this Genus, and possibly it ought to form part of 
the Generic Character, but may often be imperceptible 
from being worn, as I have it tolerably distinct in that 
Mr. P» thinks might be denominated C* decussate. 
