312 GASTEROPODA OF THE INFERIOR OOLITE. 
245. Cirrus Caxisto, d@’Orbigny, 1850. Plate XXV, fig. 1 (British variety). 
1850. Turso Catrtsto, d’Orbigny. Prodrome, vol. i, p. 300. 
1852. _— — — Terr. Jur., 1, p. 345, pl. eecxxxii, figs. 9, 10. 
1879. Crrrvs Cazisto, d’Orbigny, sp., J. Buckman. Proc. Dorset N. H. Field 
Club, p. 139, pl., figs. 6, 6 a. 
1884. Hamusina Caxisro, d’Orbigny, sp., Cossmann. Et. Bath., p. 249, pl. xiv, 
fig. 5. 
Bibliography, §c.—Rather than make a new species on this occasion I prefer 
to follow the example of J. Buckman, and identify the Coker fossils with 
d’Orbigny’s species. There are certain difficulties which present themselves with 
respect to “* Turbo”? Calisto. The type required some restoration, and thus it 
came to pass that d’Orbigny and Cossmann have differed somewhat as to the 
interpretation to be placed upon the fragments at their disposal. Moreover the 
French specimen is said to come from the Bathonian of Luc, whereas it is 
important to remember that no species of Cirrus or of Hamusina is known from 
the Great Oolite of this country, nor even from the Upper Division of the 
Inferior Oolite. 
D’Orbigny’s original diagnosis in the ‘ Prodrome’ fits our specimens very well : 
“Magnificent sinistral species, whose convex whorls are striated spirally [en long] 
and ornamented with thick transverse undulations near the suture.”” The Calisto- 
group includes Cirrus pyramidalis and Cirrus varicosus, and appears to be 
connected with the Leachi-group through var. d of the latter species and its 
modifications. 
Description : 
Length . : , : . 50mm. 
Height of body-whorl to total length .. = ae VOU: 
Spiral angle . : : 00m 
Shell sinistral, turbinate, umbilicated; apical conditions unknown. The 
number of whorls is conjectural, but the indications point to about ten, as there 
is every probability that the spire contracts with a concave spiral angle. The 
sutures of the lower whorls are wide, almost to gaping. The umbilicus is funnel- 
shaped, and of moderate width. There is no need to add further to d’Orbigny’s 
description. 
Relations and Distribution.—The differences which separate this species from 
Cirrus pyramidalis are little more than varietal, such differences being accentuated 
by change of matrix. What I have termed the British variety of Cirrus Calisto is 
not very uncommon at Coker, though generally much smaller than the figured 
specimen. These specimens bear considerable resemblance to each other, so that 
