218 
PALEONTOLOGY OF NEW YORK. 
The figures of Leptcena Barabuensis, given by Whitfield, represent internal 
casts of both valves indicating the existence of a supported spondylium in 
each.* * * § It may be that Billings’ Orthis ? Armando,^ from the Quebec group, 
is an allied species with a radially striated exterior. 
The relations of these shells to Stricklandia = Stricklandinia are not 
remote in these points of structure, and it may be inferred that they represent 
the inception of the structure which is exhibited by the Stricklandinias of the 
later Silurian and the Devonian. In the contour of the exterior a slight varia¬ 
tion is presented by the Triplesia primordialis, Whitfield, | from the Potsdam 
sandstone of Adams county, Wisconsin, and the CamareJla calcifera, Billings, 
from the Quebec group.§ By the greater development of the median fold and 
sinus the form of the shell becomes subtrihedral and resembles, not a little, 
some of the Trenton limestone species of Triplegia; but Camarella calcifera 
possesses a very small spondylium in the pedicle-valve and probably one in the 
brachial valve also. At present there seems no valid reason for excluding 
these shells from the genus Syntrophia. They evidently bear no relation to 
Triplegia. 
* Geology of Wisconsin, vol. iv% pi. i, figs. 6, 7 ; pi. iii, fig. 6. 
t Palseozoic Fossils, vol. i, p. 303, figs, a, h, c. 
I Geology of Wisconsin, vol. iv, p. 172, pi. x, figs. 1, 2. 1882. 
§ Canadian Natin-alist and Geologist, vol. vi, p. 318. 1861. 
