92 
PALEONTOLOGY OF NEW-YORK. 
All the specimens of this species which have fallen under my observation are casts, and 
these have often been much compressed ; and, as they are usually replaced by siliceous material, 
they are rough and irregular. I have referred the species to Murchisonia, to which genus it 
more probably belongs than to Loxonema. In the specimen figured by Mr. Conrad, there are 
a few folds on the last volution, but these are not the remains of striae ; and since we do not 
yet know of the existence of a true Loxonema in the middle silurian period, we should re¬ 
quire unequivocal proofs of its character before referring a specimen from this geological 
position to that genus. 
Fig. 7 a. A young specimen of this species. 
Fig. 7 b. An older specimen of the same. 
Fig. 7 c, d. Two specimens of the largest size observed; the last one wanting one or more of 
the upper volutions. 
Position and localities. The smaller individuals of this species occur in the shale below 
the ore bed in Wolcott; and the larger specimens have been found at Medina, Orleans 
county, and at Reynale’s basin in Niagara county. ( state Collection.) 
487. 8. BUCANIA STIGMOSA («. sp.). 
Pl. XXVIII. Fig. 8 a-e. 
Compare Bucania punctifrons, Pal. N. York, Vol. i, pag. 187, pl. 40, fig. 1 a, b, c, d. 
Convolute, suborbicular j volutions - ?, somewhat rapidly enlarging towards the aperture, 
which is abruptly expanded with a sinus on the dorsal margin; back of the shell rounded, 
with a sharp carina along the centre; sides of the volutions somewhat rounded, and abruptly 
depressed into a deep umbilicus ; surface marked transversly by elevated lines, diverging and 
ascending from the carina, and arching over the side into the umbilicus ; longitudinally marked 
by elevated lines parallel to the carina ; intermediate spaces rhomboidal or oval. 
This shell resembles in its general character B. punctifrons of the Trenton limestone, and 
possesses characters intermediate between that species and B. sulcatina. 
The surface of this species is regularly decussated by arching transverse and longitudinal 
strife, leaving rhomboidal spaces between them. Where these elevated lines are somewhat 
worn, the spaces appear like oval depressions or scars, with the separating lines not strongly 
■defined. In this condition the surface resembles B. punctifrons; but in all the specimens of 
that shell examined, there are no direct longitudinal striae visible, and the arching transverse 
ones are very inconspicuous; the puncta, moreover, are proportionally smaller than in the 
present species. 
The casts of this species, where the last volution is incomplete, are scarcely distinguishable 
from B. punctifrons. The species is quite rare, and all those observed are more or less 
imperfect. 
