GASTEROPODA. 315 
P PreropontA, D’Orbigny. 
Type, P. inflata, D’Orbigny. 
Fossil, 8 species. Chalk. France. 
Shell oblong, ventricose, spire elongated ; aperture oval, lip 
slightly expanded, notched in front, and with a tooth-like ridge 
internally, remote from the margin. 
P TORNATINA, A. Adams. 
ype, L. voluta. Pl. XIV., Fig. 5 
Shell cylindrical or fusiform, spire conspicuous, apex sinistral, 
suture channeled, columella callous, 1-plaited. 
Animal with a broad, trigonal head, rounded in front; ten- 
_tacular lobes triangular, seals eyes at their outer bases : foot 
short, truncated in front. 
Distribution, 24 species. West Indies, United States, Medi- 
terranean, Philippines, China, Australia. On sandy bottoms, 
ranging to 36 fathoms. (Adams.) 
Fossil, 13 species. Tertiary. 
Volvula, Adams (Bulla acuminata, Brug.), is a small con- 
yoluted shell, with the spire concealed, and the columella 
obsoletely folded; it is referred to Cylichna by Lovén, to 
Ovulum by Forbes, Distribution, 12 species. Britain, Medi- 
terranean, Asia. fossil, Pliocene—. Suffolk. 
Famizuy IJ.—BuLLIDz. 
Shell globular or cylindrical, convoluted, thin, often punctate- 
striated ; spire small or concealed; aperture long, rounded and 
sinuated in front; lip sharp. No operculum. 
Animal more or less investing the shell; head a flattened 
disk,* with tentacular lobes, often united ; eyes immersed in the 
centre of the disk, or wanting; foot oblong, furnished with a 
posterior lobe (meta-podiwm), and side-lobes (epipodia); gill 
single on the right side of the back, covered by the shell; 
mantle-margin simple or expanded, and enveloping the shell. 
Lingual dentition very various; central teeth often wanting, 
laterals single or numerous. Gizzard armed with calcareous 
plates. Sexes united. 
* The cephalic expansion of the Bullide is formed by the fusion of the dorsal and 
oral tentacles. (Cuvier.) The tentacular lobes, or posterior part of the disk, is sup- 
plied with nerves from the olfactory ganglia; the anterior portion of the disk receives 
_ branches from the labia] nerve, which comes from the front margin of the cerebroid. 
_ (Hancock.) 
P2 
