305 
Lorraine Faunas of New York and Quebec 
. c 
37. Ctenodonta lorrainensis, sp. nov. 
{Plate III, Figs. 8 A, B) 
Shell rotund in outline^ the length and width being about equal. 
The outline, however, is not strictly circular, there being a slight 
tendency toward angulation at the posterior extremity, owing to 
a straightening of the posterior part of the arcuate hinge-line, as 
in Ctenodonta pectunculoides, Hall, from the Mt. Hope and Fair- 
mount beds of the Maysville division of the Cincinnatian, at Cin- 
cinnati, Ohio, In the latter species, however, the tendency is 
toward a greater length than height of the valves, while in Cteno- 
donta borealis, the tendency is toward a slightly greater height 
than width. This results in a less angulate posterior outline. 
Moreover, the height of the hinge area, compared with the rest of 
the shell, is less. Surface with very fine concentric striae, readily 
seen only under a lens. 
Ctenodonta cingulata, Ulrich, was described from the Gasteropod 
layer at Marble Hill, Indiana. This is a layer several feet thick, 
and about 65 feet above the horizon at which Leptaena richmond- 
ensis-precursor, and Dinorthis carleyi, the characteristic fossils 
of the middle part of the Arnheim, occur. Ten feet below this 
Gasteropod layer, at Scott Hill, in Trimble county, Kentucky, 
there is a horizon full of Tetradium and Stromatocerium, imme- 
diately overlying a zone, about 15 feet thick, in which Homotrypella 
hospitalis is common. This gasteropod layer is regarded as be- 
longing to the lower part of the Waynesville section, although 
the characteristic brachiopod fauna of the Richmond is found in 
this part of Indiana and Kentucky only at a considerable dis- 
tance above the Gasteropod layer. Compared with Ctenodonta 
lorrainensis, Ctenodonta cingulata is larger, has a much thicker shell, 
the hinge area is higher, especially at the beak, and the teeth here 
are much longer, narrower, and more crowded. 
Ctenodonta pulchella. Hall, was described from the black slate 
near Watertown, New York. This black slate is interbedded 
with the limestone at the base of the Trenton section. The 
specimen represented by Figs. 12a, b, on plate 82, of vol. I, 
Paleontology of New York, is listed as number 1064 in the collec- 
tions of the American Museum of Natural History. This species, 
judging by the published figure, is readily distinguished from 
