PLEUROTOMARIA. 419 
not the case with the fossils now under consideration. Yet for these d’Orbigny’s 
description and, to a certain extent, his figures answer exceedingly well. 
The following may be taken as representing the dimensions of British 
specimens : 
Height : : ; : . 25 mm. 
Basal diameter ; ; : . 30mm. 
Spiral angle . : ‘ ioe. 
My specimens are somewhat smaller than the French ones, but the spiral 
angle, shape, and ornamentation are almost identical. If there is any difference, 
the whorls in d’Orbigny’s figured specimen are rather more angular. 
The specimens which I refer to Pl. amata occur principally at Louse Hill, in 
the upper part of the Humphriesianus-zone. They evidently belong to the 
Fasciate, though restricted in size as compared with the bulk of that section. 
358, PLEUROTOMARIA TRANSILIS, d’ Orbigny, 1854. Plate XXXVI, figs. 4, 4a. 
1854. PLEvRoToMaRIA TRANSILIS, d’Orbigny. ‘Terr. Jur., vol. ii, p. 482, 
pl. ceclxxxvi. 
Syn. _— GYROCYCLA, var. TRANSILIS, Deslongehamps. Vol. cit., 
p- 60, pl. vii, fig. 1. 
The specimen figured in the accompanying plate has a spiral angle of 58°, and 
is without umbilicus. On the whole it tallies fairly well with the figures and 
descriptions of the French authors, especially Deslongchamps, of this member of 
the Gyrocycla- or Fasciata-group. There are two specimens in my collection from 
the Parkinsoni-zone of Burton Bradstock. 
359. Pievroromarta ALimena, d’Orbigny, 1850. Not figured. 
1850. Pxrevroromarta AnimeEna, d’Orbigny. Prod., i, p. 268. 
1854. — —_ — Terr. Jur., vol. ii, p. 462, pls. 
ece]xxvii and ecelxxviil, fig. 1. 
Syn. — GYROPLATA, var. HQuistRiata, Deslongchamps. Vol. cit., 
p- 57, pl. vi, fig. 4. 
Since it is probable that the varieties xquistriata and inexquistriata merely 
represent different stages or conditions of the same species, it might be permissible 
to retain the specific name gyroplata. Provisionally, however, we may accept 
d’Orbigny’s name Alimena. 
