AMPHIBOLIDA—SIP HONARIID A. 109 
appendage of the mantle, with, in Siphonaria, a branchia in 
addition. 
Three families are admitted. 
Spiral, operculate. Amphibolide. 
Conical (limpet-like),not operculate. Siphonariide, Gadiniide. 
Famity AMPHIBOLIDZ. 
Shell spiral, subglobose, operculated. 
Animal with the external features and dentition of the pulmo- 
nata, but the respiratory cavity only communicates with the 
free air by asmall valvular opening. Aquatic, living in brackish 
water. 
They partake of the characters both of the aquatic pulmonata 
and of the Ampullariidz, and might be considered as related to 
that family perhaps quite as much as to the former. 
AMPHIBOLA, Schumacher, 1817. 
Syn.—Ampullacera, Quoy, 1832. Thallocera, Swains., 1840. 
Distr.—New Zealand. A. nuax-avellana, Chemn. (ciii, 41). 
Shell subglobose, rather thick, rugose, umbilicated; spire 
short, whorls shouldered above; umbilicated ; aperture suboval; 
eolumellar lip callous; columella flattened and reflected ; outer 
lip sinuous posteriorly ; operculum corneous, subspiral. 
Lingual membrane large, very broad, expanded, and long, with 
a central space or line scarcely defined; teeth numerous, equal, 
similar, four-sided, rather longer than broad, in straight cross- 
lines, with a bread rounded lobe, rather more sinuous on the inner 
than on the outer side of its front edge. Eyes sessile on the 
front part of the cephalic disk formed by the expanded tentacles. 
Respiratory cavity closed, except a small valvular opening on 
the right side. 
The animals of this family inhabit salt marshes near the sea, 
the living shells sometimes having Serpule attached to them. 
They appear to respire the free air. The Amphibolide offer an 
exception to the general rule, that pulmonifers with a closed 
mantle-cavity are destitute of opercula. They live in pools of 
brackish water, and at certain seasons bury themselves in the 
sandy mud. The New Zealanders collect and employ them as 
articles of food. 
AMPULLARINA, Sowb., 1842. Shell thin, globular, umbilicated; 
spire short; whorls rounded ; inner lip simple; outer lip sinuous 
in the middle. A. fragilis, Quoy (ciii, 42). 
Famity SIPHONARIID &#. 
Characters those of the typical genus. 
SIPHONARIA, Sowerby. 
Distr.—90 sp. Cape, India, Philippines, Australia, New Zea- 
