104 
PALEONTOLOGY OF NEW YORK. 
from the Paradoxides Beds ; A. subconica and A. disparirugata, Kutorga, from 
the primordial beds of Russia; A. Nicholsoni and A. ? costata, Davidson, from the 
Llandeilo. The last species is strongly ribbed on its exterior, but its generic 
relations are too uncertain to allow this fact to be regarded as adding a new 
feature to the genus. 
Genus CONOTRETA, Walcott. 1889 * 
PLATE IVk, FIGS. 16-21. 
1889. Conotreta, "Walcott. Proceedings National Museum, vol. xii, No. 775 ; Advance Sheet, Dec. 10. 
Diagnosis. The pedicle-valve is conical, its height being greater than its 
length. The apex is more or less broken on all the specimens, but in a single 
minute valve from Covington, Kentucky, there is evidence of the external 
opening of the sipho. From the apex, a shallow furrow extends to the poste¬ 
rior margin, increasing in width downward. In the smaller specimens the 
posterior wall of the shell conforms to the curvature of the rest of the surface, 
interrupted only by the longitudinal depression, but, with increase in size, 
this area becomes distinctly flattened, as in Acrotreta. Surface covered with 
sharp concentric strim which make a slight upward curve as they cross the fora- 
minal groove. 
The casts of the interior show a strong apical callosity surrounding the 
probable position of the foramen. This is somewhat produced anteriorly into 
a short sharp ridge, on either side of which lie two other ridges, with evidence 
of a third on the lateral slopes. Upon the largest of the specimens these ridges 
seem to have been hollowed at their extremities. 
Type, Conotreta Rusii, Walcott. 
* a preliminary list of the genera of the palaeozoic brachiopoda, published in the Eighth Annual 
Report ol the State Geologist, 1889, p. 48, the. term Gelnitzia was used for this genus, a description of which 
had at that time been prepared from material in our hands, obtained from the Utica horizon at Covington, 
Kentucky. It would have been necessary to withdraw this name, as it had already been in use for a genus 
of fossil plants (Endlicher, Synopsis Coniferarum, p. 281. 1847). Meanwhile Mr. Walcott has described 
the genus from specimens from Trenton Falls, in an advance sheet of the Proceedings o'f the National 
Museum, privately circulated. We have been permitted to make use of his specimens for study and 
illustration. 
