412 
PALAEONTOLOGY OP NEW-YOPK. 
ADDENDA. 
Trematospira ? nobilis. 
PLATE. 
Rhynchospira nobilis : Hall, Thirteenth Report on the State Cabinet, p. 83. 1860. 
This species was omitted in its proper place, in the hope of being able 
to determine its true relations; but the result has not been quite satis¬ 
factory. It appears, however, to be more nearly related to the Genus 
Trematospira than to Rhynchospira ; and it may be found to differ from 
either of these when the internal characters shall be fully ascertained. 
Shell large, broadly subovoid; surface plicated. 
Ventral valve with a broad mesial sinus ; the beak large and truncated 
by a large round foramen, the lower side of which is hounded by the 
summits of the deltidial plates : margins of the valve subalate a little 
below the beak. 
Dorsal valve the more gibbous, with a broad, moderately elevated mesial 
fold. 
Surface marked by numerous angular elevated plications, which are 
sharply crenulated on the summits ; the sides and intermediate spaces 
finely and evenly striated. On the mesial fold there are from nine to 
eeven plications, and a corresponding number in the sinus. 
The interior of the ventral valve shows a strong tooth on each side 
at the base of the fissure; the rostral cavity is limited by a callosity, 
and the muscular area is strongly marked and somewhat quadrate in 
form, as far as observed. 
The interior of the dorsal valve shows strong crural processes exten¬ 
ding from the hinge-line for a short distance, when they become slender 
and flattened; and below this they curve and send off a process towards 
the centre of the shell, as in others of the genus, and similar to that of 
Terebratula. 
Geological foi'mcdion and locality. In the Hamilton group ; at Darien, Genesee 
county, New-York. 
