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, ranging 
from the Silurian to the Tertiary, but is rare in the last named. 
Scissurella, d’Orbigny ; epipodium with tentacles ; right ctenidium mono- 
pectinate (Fig. 128). Schismope, 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, Léveillé ; Devonian 
and Carboniferous. Kokenella, Kittl; Trias. Ditremaria, d’Orbigny ; 
Jurassic. Polytremaria, de Koninck; Carboniferous. Trochotoma, 
Deslongchamps; Trias and Jurassic. Cantantostoma, Sandberger ; 
cae é 
LE Ss 
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t/ od 
Fie. 127. 
Pleurotomaria, with the pallial cavity laid open, right-side view. a, anus; aa, aorta; a.v, 
afferent branchial vessel; br.g, branchial ganglion; ¢c.c, cerebral commissure ; co, columellar 
muscle ; cr, crop ; ¢.v, efferent branchial vessel; /, foot; g, right or minor gill; g.d, genital 
duct; gg, gonad ; h, heart in the pericardium ; hy.g, hypobranchial gland; in, intestine; Li, 
liver ; /.k.0, opening of the left kidney; m, mouth; m.s, mantle slit; od, odontophore ; oe, 
oesophagus ; op, operculum ; os, osphradium ; pe.c, pedal cord ; 7, rectum ; 7.k, right kidney : 
r.k’, anterior part of ditto (dotted line) ; 7.k.0, opening of the right kidney ; 7.s, radular sac ; s.9, 
salivary gland ; sp.c, spiral caecum ; st, stomach. (After F. M. Woodward.) 
Devonian. Murchisonia, d’Archiac and Verneuil; Cambrian to Trias. 
Odontomaria, Roemer; Devonian. Famity 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—Bellerophen, Montfort. Huphemus, MacCoy. Salpingo- 
stoma, Roemer. Trematonotus, Hall.  Cyrtolites, Conrad. Faminy 3. 
EvompHaipAr, de Koninck. Also an extinct family, extending from 
the Cambrian to the Cretaceous. Spire slightly prominent ; umbilicus 
deep ; operculum calcareous. Genera—Huomphalus, Sowerby.  Strapa- 
rollina, Billings. Ophileta, Vanuxem. Macluwrea, Lesueur. Platychisma, 
MacCoy. Straparollus, Montfort. Phanerotinus, Sowerby. Discoheliz, 
