28 MOLLUSCA FROM THE GREAT OOLITE. 
PuRPUROIDEA GLABRA. Plate IV, figs. 5, 5a, 6, 6a. 
P. Testa turbinatd, ovata; spird easertd ; anfractibus 5—6 angulatis, angulis tuberculos 
10 gerentibus ; anfractu ultimo ventricoso, levi, basi truncatd ; aperturd magna. 
Shell turbinated, ovate; spire elevated; whorls 5—6 angulated; angles tuberculated ; 
tubercles 10 in a volution; the last whorl ventricose, smooth, the base truncated; the 
aperture large. 
In the young state the spire is simply convex, without tubercles, which are only faintly 
visible upon the last whorl. In every stage of growth the tubercles are less conspicuous 
than in either of the other two species, and the surface of the last whorl is entirely destitute 
of ribs and of a second circle of tubercles; the spire is smaller than in P. nodulata, but 
more elevated than in P. Moreausia. The length of the aperture is three fifths of that of 
the entire shell. 
Locality. It accompanies the other congeneric forms in the Minchinhampton Great 
Oolite, but is very much the most rare of them. The proportion of each species is probably 
as follows: P. Moreausia, 50; P. nodulata, 5; P. glabra, 1. 
a 
PurpurombEA NoputaTa. Plate V, figs. 1, la, 2, 3, 4. 
Movrex noputatus, Young and Bird. Geol. of Yorkshire Coast, p. 245, t. 11, fig. 3. 
—  tuBERosus, Sow. Min. Con., t. 578, fig. 4; but not t. 229, fig. 1, which is a 
Tertiary shell. 
Purpura Laprerrea, Buvignier. Mém. Soc. Philomath. Verdun, 1843, p. 27, 
pl. 6, fig. 21. 
PURPUROIDEA NopuULATA, Lycett. Annals of Nat. Hist., 1848, p. 250. 
Mvrex TuBeErosts, Brown. Illust. Foss. Conch., p. 59, pl. 34, fig. 19. 
P. Testa turbinatd, ovata ; spird easertd ; anfractibus 5—6 angulatis ; angulis tuberculos 
(9—11) plerumque elatiores gerentibus ; anfractu ultimo subventricoso, tuberculis binis 
cincto, prope basin transverse carinato ; tuberculis inferioribus minoribus, approximatis et in 
costulis longitudinalibus obliquis productis: apertura magna subquadratd, lubro dextro 
stnuato. 
Shell turbinated, ovate ; spire elevated; whorls 5—6 angulated ; the angles tubercu- 
lated ; the tubercles usually elevated, 9, 10, or 11 in a volution; the last whorl ventricose, 
encircled with two rows of tubercles ; those on the second row are much the smaller, and are 
more closely arranged, and prolonged into longitudinal oblique ribs, which are sometimes 
nearly obsolete ; below the ribs is a transverse keel, placed near to the base of the shell. 
The aperture is of moderate size, the outer lip being much sinuated. 
The first two or three whorls are convex, and destitute of tubercles; the tubercles 
vary much in size in different specimens—when very much elevated they are com- 
pressed laterally. In the young state, the apex of the spire is more acuminated, the surface 
