4 The American Geologist. July, iss»4 
my Belvidere section in paleontologie character and strati- 
graphic position). It is therefore ]><tssible that recedens may 
prove to be a species distinct from terminalis, when future 
explorations in the Alternating- beds shall lead to the discov- 
ery of tin- hinge of undoubted terminalis. 
LIMOPSIS SUBIMBRICATUS. sp. nov. 
Plate I, figs. 6—8. 
Shell small, obliquely subrotund, or obliquely rotund-quad- 
rilateral, of moderate convexity; beaks placed a little in ad- 
vance nf the middle, small hut distinct, giving the dorsal 
outline of the shell an apiculate aspect; hinge-plate ample, 
but gradually narrowed to a strait in the mid-part where its 
lower border is gently subangulated at a point a little back 
of that immediately below the beaks; denticles about twenty- 
three in number, arranged in a divaricate series, median and 
terminal denticles short and minute, the intermediate larger 
and elongate denticles for the most part curved or angulated; 
outer surface of shell smooth, except usually for a few re- 
mote, unevenly distributed, coarse, concentric growth-lines, 
or incipient imbrications; margin entire. 
Measurements. — Hight 19; length 19; breadth 10 mm. 
Occurrence. — Common in No. .lot' the Belvidere section, south of the 
railway station. 
NUCULA CATHERINA. sp. nov. 
Shell small, compressed, triangular, or cuneate-ovate ; the 
entire exterior ornamented with numerous concentric rows of 
small, closely set, compressed, hyphen-like tubercles, with one 
or two distal, broad, deeply-impressd, concentric growth-lines, 
and with delicate radial strife ; each tubercle set so that its 
trend agrees with the direction of the subjacent concentric 
growth-line, and all of the tubercles being arranged not only 
in concentric series but at the same time in quincunx order. 
so as to form two sets of intersecting, oblique, and gently 
curving rows. 
Measurements. — Hight 10.5; length 15; breadth 5 mm., in 
a small specimen. An imperfect larger specimen indicates 
dimensions at least one and a half times these. 
Occurrence. — In Xo. 3 and in the t ransition from No. 4 to No. :'. of the 
Belvidere section, one and a half to two miles southwesl of tin' Belvi- 
dere railway stal ion. 
None of the three type-specimens show the hinge charac- 
