GASTEROPODA. 455 



Dr. Rudolph Bergh. (Copenhagen, 1853.) It exhibits two modifien- 

 tions : — 



1. Lamellaria persplcua, teeth 1. 1. 1., median with a bifid base, apex 

 recurved, denticulated ; laterals large, trapezoidal, hooked and serrulate. 



2. L. Groenlandica (Oucidiopsis, Beck.) and L. prodita, Loven, teeth 

 3. 1. 3., exactly as in Velutina (fig. 246). The dental canal is spiral. 



Fam. 8. Cancellariadce : teeth 3. 1. 3. or 0. 

 Cancellaria (teeth 0.) Ti-ichotropis, Ceritliiopsis ? 



Loven places Triclio- 

 tropis in the same family 

 with Velutina; Cancella- 

 ria is very closely allied, 



though it wants both teeth / ^^ ^^0\ /^ ""'">«- / 



and operculum. Mr. Cou- 

 thouy describes Trichotro. ^'^- ^^^^ Trichotropis horealis. (Waringtoi..) 



fis cancellcda as having a muzzle like Litorina. 



Fam, 9. Tyramidellid^ : teeth 0. 



Pyramidella. Aclis. Eulima. Monoptigma. (Lea.) 



The Pyramidellidce are related to Tornatella, which has numerous similar 

 teeth (p. 180). 



? Scalaria ; uncini numerous, similar. 



? lanthina ; dentition like Testacella (if the two halves were united by 

 their outer margins), p. 148. 



SECTION B.— Phytophaga, Lam. {Rostrifera, Loven). 



Fam. 10. Turritellida: teeth 3. ]. 3. (p. 132). 

 Turritella. Caecum. Vermetus. Siliquaria. 



Fam. 11. CeritUadce: teeth 3. 1. 3. (p. 127). 

 Cerithium. Triforis. Potamides. Planaxis? 



]Mr. Wilton has examined the dentition of four CeritUadce ; the teeth are 

 broad, as in Melaniadce, with incurved and dentated summits. In Cerithi- 

 dium the median teeth are slender with minute hooks. 



Fam. 12. Melaniad<s: teeth 3. 1. 3. (p. 130). 

 Melania. Paludestrina. Tanalia. Melanopsis. Pirena. 



Fig. 248. Pirena atra. (Wilton.) 



