NATURAL SCIENCES OF PHILADELPHIA. 
123 
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Brach. pi. xxiii. tig. 19-21.) The ribs, however, are more numerous, and the 
frontal commissure more deeply sinuate. 
CENTRONELLA, Billings. 
Centronella Allei, n. sp. Shell large to medium size, terebratuliform 
greatest width a little anterior to the middle, contained one and one fourth 
times in the greatest length. Ventral valve somewhat ventncose, full to the 
immediate vicinity of the margin, especially along the cardl ^ a ^ 
larly arching from beak to anterior margin, highest m the middle , anterior 
margin with a barely perceptible truncation; no sinus or fold present , beak 
produced beyond that of the dorsal valve, truncated and circularly perforate 
at the extremity ; dental lamellae more than one-fifth the whole length of the 
valve; muscular scars, consisting of one faint media ^, 1 lme f r + . impr 1 e ®f° n f> nT . 
each side of which is another, all reaching to the middle of the valve. Dor¬ 
sal valve with its short imperforate beak closely concealed under that of its 
fellow, slightly truncate in front, but without mesial fold or sinus , regularly 
arched from beak to frgpt, highest in the middle, exhibiting a convexity 
equal to that of the opposite valve. Muscular scars consisting of a famt but 
distinct linear median impression, with a much deeper linear impression on 
each side, and a very faint one exterior to each of these—the three principal 
impressions reaching to the middle of the valve. Shell thin, stony and so id ; 
structure beautifully punctate under a lens ; general surface polished, mark¬ 
ed by a few feeble concentric lines of growth. 
Length of ventral valve, *66 (100) ; breadth, -41 (62) ; convexity, 19 (29). 
The dorsal valve above referred to comes from bed ‘ No. 6, at Burlington, 
the other specimens are apparently from “No. 5.” “ White collection o 
the University of Michigan. Also near Hamburg, Illinois, and at ialmadge, 
Summit county, Ohio. Whittlesey’s collection. 
Though the peculiar loop of Centronella has not been seen in these speci¬ 
mens, the characters given are so closely conformable with that genus that 
the reference can scarcely be questioned in the present state ot <oui knowledge. 
It is a larger, more ventricose and more elongated shell than C. Julia . 
Centronella Julia, Win. A single small specimen of this northern spe- 
cies occurs in Whittlesey’s Collection, from “one mile east ol Orange Center, 
Cuyahoga county, Ohio.” . , , 
Specimens of this species from Pt. aux Barques, have been employed by ^ 
Prof. Hall to illustrate the characters of his genus Cryptonella, (Trans. Albany 
Inst. Feb. 3, 1863, p. 4; reprinted Amer. Jour. Sci. [2] xxxv. 399.) The re¬ 
ference of this species to Centronella was made solely in the light ol Billings' 
description and figure of that genus and comparisons with the internal struc¬ 
ture of Centronella glans/agea, the type of the genus. Prof. Hall asserts that 
the description and figure do not bear out the reference ; and, having pre¬ 
viously founded Cryptonella on the external characters of certain terebratuli¬ 
form species, he assumes that Centronella Julia affords an exhibition of the 
internal characters of Cryptonella. There is not the least doubt that the ori¬ 
ginal reference of Centronella Julia was correct; and since its internal char¬ 
acters are assumed by Prof. Hall as being those of Cryptonella , the latter 
genus is thus admitted by its author to cover the same ground as the older 
genus Centronella, and must consequently pass out of use. Prof. Hall seems to 
have suspected this result; for in a note interpolated in the New Haven edition 
of his paper, (p. 405,) he refers to a drawing of a specimen of C. glans/agea , 
showing the loop, (sent him by Dr. Rominger of Ann Arbor,) and admits that 
the loop “ shows essentially the same character as that of Cryptonella.” He yet 
insists that this character is not to be inferred from Billings’ original descrip¬ 
tion and figure ; and, expressing a doubt about the identity of Billings’ type 
species {C. glans/agea) and the one figured by Rominger, “hesitates to 
1865 .] 
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