GE'KUS LEPTOCCELIA. 
365 
GENUS LepT0C«ELIA (Hall). 
This name was proposed in the Tenth Report on the State Cabinet 
(1856, published 1857), for some forms usually referred to Terebratula 
and Rhynchonella by authors. The genus was described and illustrated 
in the Twelfth Report on the State Cabinet, 1859.* 
I have subsequently found it necessary to separate some of the species 
originally included under this genus, on account of a different internal 
structure ; but the typical forms remain as first characterized. Unfortu¬ 
nately the-specimens have not yet yielded a full knowledge of their 
interior structure. 
Leptoccelia acutiplicata. 
PLATE LVII. 
Atrypa acutiplicata : Conrad, Annual Report on the Palaeontology of New-York, p. 64. 1841. 
This species is described by Mr. Conrad as follows : “ Short, ovate 
“ acute, compressed, with six to eight acute profound plicrn; beak of 
“ larger valve acute, concave beneath the apex in front; three or four 
“ strongly marked concentric impressed lines. Locality : Near Water- 
“ ville, in Onondaga limestone.” 
The shell is planorconvex, varying in form from ovate acute to orbi¬ 
cular. The ventral valve is moderately convex, with the beak slightly 
incurved. The dorsal valve is depressed-convex, sometimes flat or con¬ 
cave from compression. 
In the greater number of specimens, the plications are from six to 
eight on each valve, strongly angular; the central one on the ventral 
valve depressed, and margined on each side by a larger one, while on 
the dorsal valve two plications are slightly elevated, giving an abrupt 
sinuosity in front. The shell is concentrically marked by strong imbri¬ 
cating lines of growth. 
# See Twelfth Report oh the State Cabinet, p. 32; and Palaeontology of New-York, Yol. iii, pp. 345 
and 447. 
