THE TEETH OF SNAILS. 



275 



These species have two niai-ginals in each row as well as the 

 central and laterals and may be given the fommla 2. 1. 1. 1. 2. 

 Planaxis has many rows and Ampullaria about 4-0. Another species 

 in the collection is Pahidomus ohesus, Phil, (freshwater) belonging 

 to the Melaniidce, and the Cyclojyhoridce (land opercnlates) are 

 represented by Leptojwma halophilum, Benson, a small species from 

 Ceylon. Belonging to the Tcenioglossa are many other well-known 

 families as yet unrepresented, notably Cyjirceidce (the " cowries "'), 

 Littorinidce (the '^ winkles '') and Naticidce. Of all these families 

 Bombay has several species, those of the last named inhabiting the 

 sandy bays. The Littorinidce. are remarkable for the extraordinary 

 length of their radnlee, usually many times longer than the animal, 

 the part not in use being coiled up like a watch spring. 



Many of the Tcenioglossa are provided with 

 two lateral jaws, sculptured with elaborate 

 patterns and file-like projections. , 



(d) Ptenoglossa (-n-rrivog == winged). 



Example : lanthina fragilis, Lamarck, Plate, 

 fig. 2, shows the whole radula which is formed 

 in two divisions with a gap in the middle. Text, 

 fig. 1 0,. shows a few teeth more highly magnified. 



Formula oo • o ■ 



CO 



The lanthinidcB float on the surface of the 

 ocean and are reputed to feed on jelly fish. 



One other family,' the ■Scalariidce, is placed 

 doubtfully with the Ptenoglossa ; in habits and 

 appearance it is very unlike lantjima. Bombay 

 has a few small and rather rare species, not yet 

 represented in the collection by their radulse. 



(e) Two families (EuUmidce and Pyramidel- 

 lidce), in which the radula and jaw are absent, 

 are classed as Oymnoglossa (yv/uvo? = bare). 



(f) Rhipidoglossa ( piirl^ = fan). 



Fig. 11. 



