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PALAEONTOLOGY OF NEW-YORK. 
8pirifera praematura (n. s.). 
PLATE XXXII. 
Compare Spirifer pseudolineatus, Hall, Geology of Iowa, pa. 645, pi. 26, f. 4. 1859. 
Compare Spirifer hirtus, White & Whitfield, Proc. Bost. Nat. Hist. Society, Yol.viii, p. 293. 1862. 
Shell transversely oval or suborbicular; hinge-line shorter than the 
width of the shell, with the cardinal angles rounded : surface not 
plicate. 
Ventral valve moderately convex, sometimes subventricose, with abroad 
and rather shallow sinus, the margins of which are not strongly de¬ 
fined : beak moderately elevated and incurved ; area small, the lateral 
margins undefined. 
Dorsal waive regularly and moderately convex, with a scarcely defined 
mesial elevation, which becomes broad and more conspicuous towards 
the front of the shell. 
'Surface marked by numerous regular subimbricating concentric lines, 
crossed by coarse radiating strise : these are often continuous, but 
always more conspicuous on the concentric lines or ridges, sometimes 
giving a pustulose appearance to the surface. 
The casts or partial casts sometimes preserve the radiating strise more 
distinctly than the concentric lines. In the perfect shell, the radiating 
striae were doubtless produced from the concentric ridges into minute 
spinules. 
The casts of the ventral valve show the cavities of rather slender but 
sometimes considerably elongated dental lamellae. The muscular area is 
somewhat narrow, and only rarely are the parts well defined. There is 
always a longitudinal impression indicating a median crest or low septum 
from the apex of the rostral cavity. 
The condition of the specimens is not such as to enable me to give a full de¬ 
scription of the species. They are either casts in friable ferruginous sandstone, or 
partial casts preserving some of the surface markings; while some specimens in a 
shaly bed have been macerated till the surface characters are obscured. It clearly 
belongs to the group of Spirifers of which /S. lineata is the type, and is closely 
