CALYPTRAID A. 211 
verse strix. Paleozoic. A connecting link between Vanikoro 
and Neritopsis ; the former having the columellar lip smooth, the 
latter insinuated in the middle, or provided with two strong 
teeth, while Naticodon has only one tooth ; as regards the thick- 
ness of the shell this transition seems equally to hold good. N. 
sptratum, Sowb. (lxiv, 76). Carboniferous; Europe. 
Famity CALYPTRAID A. 
Shell limpet-like, with the apex more or less spiral; interior 
simple, or divided by a shelly process, variously shaped, to which 
the adductor muscles are attached. 
Animal with a distinct head ; muzzle lengthened ; eyes on the 
external bases of the tentacles; branchial plume single. The 
rostrum is prominent and split, but non-retractile. 
The bonnet-limpets are found adhering to stones and shells ; 
most of them appear never to quit the spot on which they first 
settle, as the margins of their shells become adapted to the 
surface beneath, whilst some wear away the space beneath their 
foot, and others secrete a shelly base. Both their form and 
color depend on the situation in which they grow; those found 
in the cavities of dead shells are nearly flat, or even concave 
above, and colorless. They are presumed to feed on the sea- 
weed growing round them, or on animalcules; a Calyptraa, 
which Professor Forbes kept in a glass, ate a small sea-slug 
(Goniodoris) which was confined with it. Both Calyptrea and 
Pileopsis sometimes cover and hatch their spawn in front of 
their foot. 
The use of the calcareous lamina, which is the first stage in 
the formation of a columella, is to support the viscera and 
separate them from the foot or locomotive organ. 
GALERUS, Humphrey, 
Syn.—Sigapatella, Siphopatella, Lesson, Mitella, Leach. 
Distr.—Tropical and subtropical. G. Chinensis, Linn. (Ixvi, 
22,23). Fossil. L. Cretaceous—. 
Shell depressed subconical, spiral, summit subcentral, aperture 
very large, basal, with a subspiral broad lamina adhering to the 
left margin. Animal with bilabiate muzzle, buccal appendages 
short, rounded; a slightly developed, plain-edged neck-lobe ; foot 
auriculate in front. 
GALEROPSIS, Conrad. Spire more elevated. G. exrcentricus, 
Gabb. Eocene. 
InruNDIBULUM, Montfort. 
Syn.—Trochita, Schum., 1817. Clypeola, Gray. Trochella, 
Gray. 
ie aa ese tropical and subtropical. J. spirata, Forbes 
(Ixvi, 24,25). Fossil, Tertiary; U. S., West Indies. 
