GASTEROPODA. 217 
Shell thin, umbilicated ; spirally furrowed ; the ridges with 
epidermal fringes; columella obliquely truncated; operculum 
lamellar, nucleus external. 
Eoinal with a short broad head ; fontnales distant, with eyes 
on the middle; proboscis long, retractile. 
Lingual aa ition similar to velutina; teeth single, hamate, 
denticulated ; wncint 3: 1 dénticulate, 2 and 3 simple (Fig. 82), 
Fig. 82. Trichotropis borealis. (Warrington). 
Loyén places Trichotropis in the same family with Velutina ; 
Cancellaria is very closely allied, though it wants both teeth 
and operculum. Mr. Couthouy describes Trichotropis cancellata 
as having a muzzle like Littorina. 
Distribution, 14 species. Northern seas. United States, Green- 
land, Melville Island, Behring’s Straits, North Britain. 15—80 
fathoms. 1 species from Japanese seas (A. Adams). 
Fossil, 1 species. Miocene—. Britain. 
Pyruna, Lam. Fig-shell. 
Etymology, diminutive of pyrus, a pear. 
Synonyms, Ficula, Sw. Sycotypus, Br., Cassidula, Hamph. 
Cochlidium, Gray. 
Type, P. ficus. Pl. V., Fig. 6. 
Shell pear-shaped; spire short; outer lip thin; columella 
smooth; canal long, open. No operculum in the typical 
species. 
Distribution, 39 species. West Indies, Ceylon, Australia, 
China, Western America. 
Fossil, 32 species. Neocomian—. Europe, 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.) 
Sub-genera, Fulgur, Montfort P. peryersa. (= Pyrella, Sw. 
P. spirillus.) 
Rapana, Schum. P. bezoar, shell perforated. Operculum 
lamellar, nucleus external. This nppears to be a Purpura. 
Myristica. Sw. P. melongena. Pl. V., Fig. 7. Operculum 
pointed, curved. 
