GASTEROPODA. 29 
of the whorls has fine encircling strize, the second circle of tubercles is not formed, or is 
merely rudimentary, and the longitudinal ribs beneath and basal carina are both absent ; 
the last whorl has therefore a smooth aspect, which is in striking contrast with specimens of 
advanced age. The length of the aperture in the adult shell somewhat exceeds that of the 
spire; but the latter portion varies much in altitude, and occasionally exceeds the aperture 
in length. Upon the whole, the aspect of this species varies so considerably, independently 
of the changes produced by the stages of growth, that a considerable number are requisite 
for its full elucidation. It accompanies P. Moreausia, but is much more rare, probably in 
the proportion of about 1 to 10. 
The figures given by Young, Sowerby, and Buvignier, present but a remote resemblance 
to each other and to our figures, but there cannot be much doubt of their identity. Young’s 
figure represents an individual with a spire rather depressed; that in the ‘ Mineral Con- 
chology’ is from a mutilated specimen, little better than a cast. Buvignier’s figure is 
likewise imperfect, besides which, the artist appears to have represented the inner lip of a 
true Purpura. 
Locality. Minchinhampton Common. 
This species has been found in Yorkshire only in the Coralline Oolite, where casts are 
stated to be not unfrequent in the hard limestone. M. Buvignier’s specimen is from the 
ferruginous oolite of Vieil-St.-Remy. 
Family—CERITHIADE. 
Crrituium, Adanson, 1757. Brug., Lam. 
Shell elongated, tuberculated or costated, seldom smooth; spire pyramidal or cylin 
drical, composed of numerous volutions ; aperture subquadrate, terminated anteriorly by a 
short canal, which is most frequently reflected outwards and backwards. 
CrritHium avapricincetum, Groldf. Plate IX, fig. 8. 
CERITHIUM QUADRICINCTUM, Goldfuss. Petref., p. 32, t. 
3, fig. 11. 
— — Bronn. Index Palzont., p. 272. 
17 
27 
C. Testé conicd, anfractibus (10—12) quadrigonis, cingulatis, cingulis superficialibus 
quarterms granulatis ; granulis longitudinalibus seriatis. 
Shell conical, spire obtuse, whorls (10—12) rather convex ; encircled with four costz ; 
the cost are granulated, so as to form a longitudinal series. The whorls are narrow, 
the height scarcely exceeding one third of the transverse diameter; the largest specimens 
do not exceed half an inch in length, and half of that length may be considered as the 
average dimensions. 
