GASTEEOPODA. 217 



Shell thin, umbilicated ; spirally furrowed ; tlie ridges with 

 epidermal fringes ; columella obliquely truncated ; operculum 

 lamellar, nucleus external. 



Animal with a short broad head ; tentacles distant, with eyes 

 on the middle ; proboscis long, retractile. 



Lingual dentition similar to velutina ; teeth single, hamate, 

 denticulated; uncini 3: 1 denticulate, 2 and 3 simple (Fig. 82). 



Fig. 82. Trickotropis borealis. (Warrington). 

 Loven places Trickotropis in the same family with Velutina; 

 Cancellaria is very closely allied, though it wants both teeth 

 and operculum. Mr. Couthouy describes Trickotropis cancellata 

 as having a muzzle like Littorina. 



Distrihution, 14 species. Northern seas. United States, Green- 

 land, Melville Island, Behring's Straits, North Britain. 15 — 80 

 fathoms. 1 species from Jai^anese seas (A. Adams). 



Fossil, 1 species. Miocene — . Britain. 



Pyrula, Lam. Fig-shell. 



Etymology, diminutive of pyrus, a pear. 



Synonyms, Picula, Sw. Sycotypus, Br., Cassidula, Hamph. 

 Cochlidium, Gray. 



Type, P. ficus. PI. Y., Fig. 6. 



Shell pear-shaped; spire short; outer lip thin; columella 

 smooth ; canal long, open. No operculum in the typical 

 species. 



Distrihution, 39 species. West Indies, Ceylon, Australia, 

 China, Western America. 



Fossil, 32 species. Neocomian — . Eui'ope, India, Chili, Java. 



Pyrula ficus has a broad foot, truncated and horned in front ; 

 the mantle forms lobes on the sides, which nearly meet over the 

 back of the shell. Chinese seas, in 17 — 35 fathoms water. 

 (Adams.) 



Suh-genera, Fulgur, Montfort P. perversa. (= Pyrella, Sw. 

 P. spirillus.) 



Rapana, Schum. P. bezoar, shell perforated. Operculum 

 lamellar, nucleus external. This appears to be a Purpura. 



Myristica. Sw. P. mel )ngena. PLY., Fig. 7. Operculum 

 pointed, curved. 



