THE GASTROPODA 



147 



obtained in 1871, in a collection made off the Barbadoes by the 

 " Hassler" (A. Agassiz). The Moluccan species is nineteen centimetres/ 

 in height. The genus includes several hundred extinct species, rangir 

 from the Silurian to the Tertiary, but is rare in the last nai 

 Scissurella, d'Orbigny ; epipodium with tentacles ; right ctenidium n;6no- 

 pectinate (Fig. 128). Schitmope, Jeffreys; the slit at the margin of 

 the shell is closed in the adult and transformed into an orifice (Fig. 62 . 

 The following genera are exclusively fossil : Porcellia, Leveille ; Devonian 

 and Carboniferous. Kokenella, Kittl ; Trias. Ditremaria, d'Orbigny ; 

 Jurassic. Poli/tremaria, de Koninck ; Carboniferous. Trochotoma, 

 Deslongchamps ; Trias and Jurassic. Cantantostoma, Sandberger ; 



' T-*-' 



oesophagus ; op, operculum ; os. ospliradium ; pe.c, pedal cord ; r, rectum ; r.k, right kidney ; 

 ;-./.-', anterior part of ditto (dotted line); r.k.o, opening of the right kidney; r-.s, radularsac; s.g, 

 .sjilivary gland ; .-/i.c, spiral caecum ; ft, stomach. (After F. M. Woodward.) 



Devonian. Murchisonia, d'Archiac and Verneuil ; Cambrian to Trias. 

 Odontomaria, Roemer ; Devonian. FAMILY 2. BELLEROPHONTIDAE, Mac- 

 Coy. An exclusively fossil family, comprising more than 300 

 species extending from the Cambrian to the Trias. The shell is coiled 

 in one plane and has an incision in the mid -dorsal margin of the 

 aperture. Genera Bellerophcn, Montfort. Euphemus, MacCoy. Salpingo- 

 stoma, Roerner. Trematonotus, Hall. Gyrtolites, Conrad. FAMILY 3. 

 EUOMPHALIDAE, de Koninck. Also an extinct family, extending from 

 the Cambrian to the Cretaceous. Spire slightly prominent ; umbilicus 

 deep ; operculum calcareous. Genera Euomphalus, Sowerby. Strapa- 

 rollina, Billings. Ophileta, Vanuxem. Maclurea, Lesueur. PlatycJiisma, 

 MacCoy. Straparollus, Montfort. Phanerotinus, Sowerby. Discohelix, 



