S04 
PALAEONTOLOGY OF NEW-YORK!. 
Leiorhynchus globuliformis. 
PLATE LYII. 
Atrypa globuliformis : Vanuxem, Geol. Report Third Dist. New-York, p. 182, f. 2. 1842. 
I adopt the name applied by Mr. Vanuxem to some .gibbous forms of what 
appear to be Leiorhynchus. The species is spoken of as occurring “ in myriads ” 
in this group of strata in the Third District. I have nevertheless had an opportu¬ 
nity of examining but a few individuals, which are casts of gibbous dorsal 
valves, marked along the centre by four or five strong rounded plications, which 
are a little elevated above the general surface of the shell, and margined by a 
narrow elongate muscular impression. It is possible that larger collections may 
show the propriety of uniting these with L. mesacostalis. 
Geological formation and localities. This species occurs in the Chemung group 
in the south part of Otsego county, and elsewhere in the southeastern part of the 
State of New-York. 
Leiorhynclms duirius (n. s.). 
PLATE LYII. 
Shell broadly ovate, rapidly expanding in width from about the middle 
of its length, and wider than long; concave along the cardino-lateral 
margins. 
Valves moderately and almost equally convex; the ventral valve scarcely 
sinuate, and the dorsal valve with a slightly elevated fold near the 
front. 
Surface marked by twenty-four to twenty-six slender rounded plications, 
of which about six are raised on the mesial fold. Length half an inch, 
with the width a little greater. * ^ 
Of two well-marked specimens, one has^a slight fold and sinus, affec¬ 
ting only the front of the shell; the other specimen is not perceptibly 
marked by this feature. The plications or striae are finer than in any 
other species, and extend quite to the apex of the valves. 
This species is apparently from the calcareous beds of the Marcellus shale, but 
the particular locality is not known. 
