Dentition of Pulmonate Mollusks. 87 
The result of my examination of the lingual membrane throws 
light on the generic position of this species. It ean no longer 
be retained in Caracolus, a sub-genus of Helix, as proposed by 
von Martens, since it has the dentition of the Vitrinea of von 
Martens’ arrangement. It differs, however, from Zonites, in 
having no longitudinal furrows above the margin of the foot, 
and no caudal mucus-pore. It seems to belong to no described 
| genus. 
vanuius. 
Junulus stephanophora, Desh. Madeira. Dr. Hillebrand. 
Jaw strongly arched ; ends pointed; cutting margin with a sharp, greatly 
produced median projection. 
Janulus bifrons, Lowe. Madeira. Dr. Hillebrand. 
Jaw smooth, with median projection. 
Lingual membrane with 34-1-34 teeth, of which four on each side are 
laterals, all as in Zonites. 
HOLOGNATHA HELICEA. 
This section contains the genera furnished with a jaw in one 
single piece, and quadrate marginal teeth to the lingual 
membrane. 
A. JAW RIBLESS. 
I still retain this section, though several species in various 
genera have ribs on their jaw. 
Tebennophorus. (See Terr. Moll., V.) 
Tebennophorus Costaricensis, Mérch. Costa Rica. Dr. W. M. 
Gabb. 
Jaw strongly arched, of equal width to its blunt extremities. There are 
sub-obsolete anterior ribs about the centre of the jaw, the ends of five of 
which denticulate the cutting margin. 
The lingual dentition is figured on Plate VIII, fig. N. There are about 
28-1-28 teeth. The centrals have a long base of attachment, with a strong 
line of reinforcement running parallel to its margin at the lower edge and 
for a short distance at the sides. The reflection is small, and bears a short, 
stout median cusp, and small stout side cusps; all three cusps bearing short, 
stout cutting points. The lateral teeth are like the centrals, but asymmet- 
rical by the suppression of the inner cusp and cutting point and the inner 
lower expansion of the base of attachment. The marginals are but a modi- 
fication of the laterals; the inner cutting point not becoming bifid, though 
the outer one is so on the extreme marginals. There are hardly more than 
twelve perfect laterals on each side. The change into marginals is very 
gradual. 
