8^7 



MONOGRAPH 



OF 



STOMATELLIN^, 



A SUB-FAMILY OF TROCIIID.i:. 



By ARTHUR ADAMS, F.L.S., Surgeon R.N., etc. 



STOMATELLm^. 



Head broad, proboscidiform ; tentacles subulate, with a fimbri- 

 ated lobe at their inner bases; eyes on peduncles at the outer 

 bases of the tentacles ; mantle with the front edge entire ; muscle 

 of attachment crescentic, open in front; foot with a fringed, la- 

 teral membrane. 



Operculum none, or rudimentary. 



Shell more or less ear-shaped, imperforate ; aperture very wide, 

 pearly within, and with a crescentic muscular impression, inter- 

 rupted in the region of the head. 



The shells described in this monograph constitute a very natural 

 section of the TrocJddce, which family may be divided into three 

 sub-families, or Turh'mina, in which the operculum is shelly; 

 Trochina, where it is horny; and Stomatellina, in which it is 

 absent or rudimentary. The Stomatellince differ from the Halio- 

 tidcB, with which they are sometimes confounded, in the mantle 

 not being fissured anteriorly, in the muscle of attachment being 

 in the form of a horse-shoe round the sides and hind part of the 

 mantle, instead of being ovate and central, and in the shell not 

 being furnished with a series of holes. 



In their habits these Molluscs are littoral, living on coral-reefs 

 and among stones between tide-marks; the finest species prefer 

 coral reefs exposed to the action of the waves. Some of the 

 genera, as Goia and Stomatia, have considerable locomotive 

 powers, and glide (especially Genu) with some degree of celerity. 



5 p 



