GASTEROPODA. | UPPER PALZXOZOIC MOLLUSCA. 525 
Position and Locality—Not uncommon in the carboniferous limestone of Lowick, Northumberland ; very 
rare in the lower carboniferous limestone of Derbyshire. 
Explanation of Figures —P1. 3. H. fig. 9, natural size, depressed variety, front view; fig. 10, do. elevated 
variety, natural size, back view. 
PLEUROTOMARIA ANGULATA (de Kon.) 
Ref. and Syn.—de Kon. Anim. Foss. Bel. t. 37. f. 2. = Trochus acutus id. Olim. 
Dese.—Conical, periphery of body-whorl sharply angulated ; spire of five and half flattened whorls, very 
slightly convex near the upper suture, and very slightly concave near the lower one; suture a moderately 
impressed line; apical angle 95°; base very obtusely conoidal, slightly convex, sloping from the carinated 
periphery to the angular edge of a wide, deep, smooth, conical umbilicus. Surface covered with slightly unequal, 
elevated, thread-like, spiral strize, separated by flat spaces rather wider than the striae; about twelve spiral lines 
on each whorl, and about the same number on the base: band narrow, smooth, placed on the angle; mouth 
wider than long, rhombic. Diameter of average specimen four lines, proportional height %, height of mouth ~, 
width of umbilicus about “. 
The striation of this species is scarcely visible to the naked eye. From the small size of the band, and its 
coinciding with the keeled periphery, it is very difficult to distinguish, Possibly the Trochus pyramidatus may 
be only an elevated form of the same species (corresponding to the two varieties of Pleurotomaria Yvani), the 
elevation of the spire accounting for the diminished size of the umbilicus. 
Position and Locality—Rare in the carboniferous limestone of Derbyshire. 
PLEUROTOMARIA ANTRINA (Sch/ot.) 
Ref. and Syn. = Trochilites antrinus Schlot. Akad. Minch. Vol. VI. t. 7. f. 6c. = Pleurotomaria Permiana 
King, Catal. = P. Sedgwickiana How. 'T. T. N. F.C. Vol. 1.;?=P. Verneuili Geinitz, Verstein t. 3. f. 17, 
18.=P. antrina (Schlot.) King, Perm. Foss. t. 17. f. 1, 2, 6.42. Tumstallensis id. ib. f. 3, 4, 5. 
Dese.—Spire of variable elevation, composed of four and half slightly convex whorls, slightly tumid near 
the sutures above, and rather more so below; sinal band depressed, flat, rather narrow, bounded by two fine, 
elevated, thread-like keels, the lower keel being about half the width of the band above the suture on the spiral 
whorls, and slightly above the most conyex part of the periphery on the body-whorl; base rather flattened, with 
a very small umbilicus; pillar long, slightly oblique ; mouth transversely oblong, rounded. Surface marked 
with fine, obscure, unequal lines of growth arching backwards to the band, often thickened at intervals near the 
suture, forming an obscure, obtuse plication ; occasionally a few faint, obtuse, spiral strize, rather smaller than 
those bounding the band, and their own thickness apart, may be seen on parts of some specimens. Length of 
average variety seven lines; in proportion thereto, length of mouth =, width of mouth =, depth of penultimate 
whorl **, apical angle varying from 70° to 100°, the former usually large specimens, the latter extreme usually of 
small size, 75° being the most common angle, and agreeing with the above measurements. 
The spiral strize are scarcely ever distinctly visible, requiring apparently some peculiar state of preservation 
or decay to render them visible. I have traced all the gradations between the extremes of height and depression 
of the spire noted above, so as to render it certain they are of one species. The obliquity of the pillar lip marked 
by Professor King as distinguishing his P. 7vnstallensis from the present species is equally seen in both. 
Position and Locality—Common in the Permian magnesian limestone of Humbleton. 
PLEUROTOMARIA CALLOSA (de Kon.) 
Ref.—de Kon. Anim. Foss. Bel. t. 36. f. 7. 
Desc.—Globose, obtusely conic ; body-whorl large, rounded; spire short, of about four or five gently con- 
vex whorls ; apical angle 100°; sinal band of moderate width, convex, bounded by two narrow sulci, of which 
