GASTEROPODA. 



459 



The Cape limpets (e.g. P, denticulata) have a 

 minute central tooth, which is wanting in any other 

 species hitherto examined. ( Wilton) 



ORDER III. PULMONIFERA. 



Section A. 

 rous, similar. 

 Section B. 

 175.) 

 Glandina 



In-operculata. Lingual teeth nume- 

 (p. 160.) 

 Operculata. Lingual teeth 3. ]. 3. 



(P 



Fig. 256. Patellavulgata. 

 (Original: Wilton.) 



ira) has teeth like the Testacelle 

 169, Raymond, Journ. Conch. 1853). 

 The anomalous genera Siphonaria and Amphibola 

 have a dentition like the inoperculate land-snails. (Wilton). Othm {Velutina) 

 Otis has teeth similar to Conovuhis. (Clark.) 



The many points of agreement between the Litorinidce and Cyclostomidce 

 have been ak-eady pointed out (pp. 32, 174). 



ORDER IV. OPISTHOBRANCHIATA. 



The lingual dentition is ex- 

 tremely varied in the BuUida. 

 In Philine aperta there is no cen- 

 tral tooth; and the laterals, which 

 increase rapidly in size backwards, 

 have a finely denticiUated mem- 

 branous inner edge. 



In Tornatella and Bulla (phy- 

 sis) the rachis is unarmed, and 

 the lateral teeth are numerous 

 and similar ; in Acera, Cylichna, 

 and Amphisphyra, there is a 

 minute central tooth. 



Fig. 258. Philine aperta. (Wilton.) 



ORDER V. NUDIBRANCHIATA. 



The Borididcs are distinguished by 

 having a short and wide lingual mem- 

 brane with numerous similar teeth ; 

 the Solids have a narow ribbon with 

 a single series of larger teeth. In Ben- 

 Fig. 259. Dendronotus arborescens dronotus a large central tooth is 

 flanked by a few small denticulated teeth. (Alder and Hancock, PI, II 

 fig. 8.) 



The only Nudibranche with a solid upper jaw, is Mgirus punctihicens 

 (A. and H. PI. XVII. fig. 15). In other instances the two halves are arti- 



X3 



