OF SOUTHERN INDIA. 291 
volutions, ought to be retained in this genus; others with flattened and more 
eylindrical whorls and with the spire short chiefly belong to Amaura, Amauropsis, 
Littorina, and others. 
4a. Amaurella, A. Adams, 1867 (Proc. Zool. Soc., p. 311). Shell small, ovate, 
white, apex submammillate; aperture ovate, immer lip arcuate, simple, somewhat 
thickened, columella solid. The type of this genus is the species formerly described 
from the Japan seas, by the same author, as Macrocheilus japonicus. In describing 
this species in the Aun. Mag. Nat. Hist. of 1860, V, p. 407, A. Adams stated, that 
no generic distinction exists between the fossil species and the recent one which 
he had discovered. I must say, that I cannot consider the characteristics given of 
Amaurella as in any way different from those of JJacrocheilus, at least not in the 
sense in which I believe this last genus has any claim to be accepted by conchologists. 
I'am not acquainted with any cretaceous species of the Szrzrrzrrvz, but I 
have already (p. 284) mentioned, that certain tertiary species, described by Lea 
under the name of Pasithea, in form much resemble Macrocheilus. 
XXXVITI. Family, NATICID. 
The animals of the Nazzcrpx are especially characterised by the very consi- 
derable expansion of the fleshy foot, which is sometimes longitudinally folded in 
front, enveloping the shell to a greater or lesser degree; the head is small, the ten- 
tacles conically elongated, united by a veil at their base; eyes very small, generally 
immersed in the fleshy substance, and placed above on short peduncles at the outer 
‘base of the tentacles, they are said to be occasionally altogether wanting ; the mantle 
is enclosed and the operculigerous lobes generally well developed. The proboscis is 
elongated and entirely retractile; the teeth are arranged in seven series, the central 
ones being broad, with 3-5 unequal, internally curved processes, while the lateral 
teeth are elongated, at the tips more or less hooked or denticulated. ‘The gills are 
said to consist of two united plumes and some mucous fillets. 
The Naricrpz belong to the most predaceous Mollusca, especially burrowing 
in sand after bivalves, the shells of which they drill with their armed tongue, 
extracting the soft parts of the animal through the perforation. Some of them, 
according to the examinations of Prof. Troschel, possess a peculiar fleshy disc for 
the purpose of attaching themselves to those shells, which they intend to attack. 
The operculum is usually paucispiral, horny, sometimes covered with a shelly 
layer. H. and A. Adams state that it does not often correspond in size with the 
aperture, as those species which have the latter large often possess a small oper- 
culum, and on the contrary those with a narrow aperture, a comparatively large one. 
In young specimens the operculum is generally of the same size as the aperture. 
The shell is spiral, more or less globose, with a short spire and the last volution 
inflated, or more or less enlarged ; the surface smooth, polished or spirally sulcated ; 
the aperture oval or hemispherical, generally obliquely prolonged, large, anteriorly 
rounded, posteriorly angular, and often sub-canaliculated, anteriorly broadly rounded, 
entire. 
