328 
PALEONTOLOGY OF NEW YORK. 
Genus C<elospira (Hall). 
The species published under the name of Leptoccdia concatia in the third 
volume of the Palaeontology of New York, page 245, was subsequently 
found to possess internal spires, arranged in a somewhat peculiar manner, 
and connected by a strong loop. This feature rendered it necessary to 
remove the fossil from the association in which I had placed it, with Lepto- 
coilia imbricata and L. flabellites, and I have proposed for it the generic name 
Ccelospira.* 
This genus differs but little from Zygospira proposed by me in 1862,f and 
it may be found desirable to unite the two under that designation, extending 
the characters so as to include the types of both the genera ; but this can 
only be done after the discovery and examination of other species which 
may serve to unite the forms already described. 
The shells of Ccelospira are concavo-convex, having the ventral valve 
convex or sometimes subangularly arching over the concave dorsal valve. 
The surface of the shell is striated or plicated, with the plications simple 
or bifurcating, and of which two or more in the centre of the ventral valve 
are more conspicuous than the others, forming a more or less defined mesial 
fold; upon the dorsal valve there is a corresponding depression. The 
space between the valves leaves little room for the spires, and these append¬ 
ages appear to be somewhat loosely arranged, with their apices approaching 
each other. These shells are apparently fibrous in texture; and on this 
account, and from the position of the spires, they approach more nearly to 
Atrypa than to Trematospira, to the latter of which they are more nearly 
allied in external form. 
The Terebratula barrandi of the Wenlock limestone of England belongs appa¬ 
rently to the genus, being closely allied to C. disparilis (= Atrypa disparilis) of 
the Niagara group (Palaeontology of New York, Yol. ii, p. 277), holding likewise 
a similar geological position. 
* Sixteenth Report on the State Cabinet, p. 60. 1863. 
f Fifteenth Report on the State Cabinet, p. 154. 1862. 
