ANIMALS. 215 
Pleurotomaria, considering that living specimens of a species have been dredged in 
deep water off Lerwick in Shetland, “ adhering to stones like Hmarginula,” it may be 
concluded to be a ground-dwelling genus: it consequently differs from Janthina—by 
some supposed to be an allied genus—which is essentially an ocean-surface inhabitant. 
No evidence has yet come to light proving that any species are perlaccous,—a 
circumstance, which, viewed in connexion with the histology of the shell of Plewroto- 
maria crispata (Scissurella id., Flem.), is strongly in favour of the genus being essentially 
non-perlaceous. 
Pleurotomaria appears to have existed from nearly the earliest portion of organic 
time to the present moment; but the species have evidently decreased in dimensions, 
and numerical amount during the Tertiary and existing periods. 
PLEUROTOMARIA ANTRINA, Schlotheim. Plate XVII, figs. 1, 2, 6. 
TROcHILITHS ANTRINUS, Schl. Akad. Miinch., vol. vi, p. 32, pl. vii, fig. 6 ¢ (? not a, 4), 
1816. 
(?) Puevroromarta (?), J. de C. Sow. Sedgwick, Trans. Geol. Soc. Lond., 2d series, vol. iii, 
p. 118, 1829. 
(2) —_ (’) ss Phillips, Encye. Met., vol. iv, p. 618, 1824. 
— ANTRINA, Schl. Geinitz, Geea von Sachsen, p. 95, 1843. 
— CARINATA, J. Sow. De Verneuil (apud King), Bull. Soc. Géol. de France, 
2™ serie, vol. i, p. 34, 1844. 
— a Geol. Russ., vol. 1, p. 225, 1845. 
29 
—_ — Tennant, Strat. List, p. 89, 1847. 
— Prrmiana, King. Catalogue, p. 13, 1848. 
— Srepewickrana, Howse. Trans. T. N. F. C., vol. i, p. 238, 1848. 
== = » var. AMPULLA, Howse. Op. cit. 
— ANTRINA, Schl. Geinitz, Versteinerungen, p. 7, pl. ui, fig. 19 a@, 4, 1848. 
(2) — VERNEUILI, Geinitz. Op. cit., p. 7, pl. iii, figs. 17 a, 6, 18 a, 6. c, 1848. 
Diagnosis.—“ Short: conical. Whorls rounded; marked with distinct, tolerably 
regular, incremental striz. ssure-band broad; bounded on both sides by a narrow 
lnimesae 
“This species resembles the Plewrotomaria carinata of J. Sowerby, with which I 
formerly identified it; but it has a concave sinus-band and a small umbilicus: its 
colouring consists of straight and not zig-zag longitudinal bands, as in the latter: it is 
spirally threaded, and its pillar-lip is perpendicular.”” The specimen represented by 
fig. 19, pl. i, m the ‘ Versteinerungen,’ is more distinctly marked with lines of growth 
than any that have occurred to me. Occasionally specimens are found with the spire 
1 Vide Jeffreys, Annals and Magazine of Natural History, 2d series, vol. iv, p. 300. 
2 Vide Geinitz, ‘ Versteinerungen,’ p- 7. ‘Ein kurz-kegelformiges Gewinde von vier stark gewolbten 
Umgingen, in deren Mitte eine breite Spaltdecke von zwei schmalen Leisten begrinzt wird. Die ganze 
Schale ist mit deutlichen, ziemlich regelmassigen Zuwachstreifen verziert.”’ 
3 King, Catalogue, p. 13. 
