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PALEONTOLOGY OF NEW YORK. 
short compared with those of a typical Athyris and make but a short curve within 
the primary lamellae. A very peculiar feature of this structure is the absence 
of an upright athyroid stem, the bifurcation of the intercalary lamellae taking 
place at the point of union of the lateral supports of the loop, the whole 
apparatus having thus, the form of an inclined X, with its upper tips curved 
outward. The demonstration of this structure justifies the conclusion of Mr. 
Glass that the species is not an Athyris, but another of such incipient stages 
of athyroid structure as are represented by Meristina, Whitpieldella, etc., 
though lacking the upright jugal stem which all those possess. Mr. Glass has 
proposed to place the species under Davidson’s genus Bifida, where it might 
perhaps rest, were we confident of the accuracy of the determination of the 
loop in B. lepida as given by Mr. Davidson (see discussion of the genus 
Bifida), but as the shell certainly represents a distinct variation of structure 
from any heretofore observed, it will be far more satisfactory to recognize this 
fact by giving the species some distinctive term, as Glassina. 
Subgenus SPIRIGERELLA, Waagen. 1883. 
1862. Athyris, Davidson. Quartei-ly Journal Geol. Soc. London, vol. xviii, p. 28, pi. i, fig. 8. 
1863. Athyris, De Koninck. Foss. Paleoz. de I’lnde., p. 33, pi. ix, fig. 8. 
1867. Athyris, Vbrchere. Jour. Asiat. Soc. Bengal, vol. xxxvi, pt. ii, p. 210, pi. ii, figs. 1, 1 ci. 
1874. Athyris, Derby. Bull. Cornell University, vol. i, No. 2, p. 7, pi. i, fig. 7. 
1883. Spirigerelld, Waagen. Palseontologia Indica, p. 450. 
Dr. Waagen has proposed to separate from Athyris a considerable group of 
species, under the term Spirigerella. Adhering pretty strictly to the broader 
characters of the type-species, S. Derbyi, Waagen, it would seem that his asso¬ 
ciation of species* under this term is to a certain degree heterogeneous; at all 
events, the group conforming in exterior characters to Spirigerella Derbyi, has 
a peculiar expression not shared by such forms as S. grandis, S. media, S. ovoid- 
alis, and S. fusiformis, Waagen. 
The distinctive features of Spirigerella are as follows: Exteriorly the 
shells are elongate, but may be transverse; their contour shows a decided tend- 
* Ten in number, from the Carboniferous I’ocks of the Salt-Range. 
