MANUAL OF THE MOLLUSCA. 
Fossil, 16 species. The greater number belong to the Great 
Oolite, others occur in the Kelloway Rock. England, France. 
Mesostoma, Deshayes, 1864. 
Example, M. grata, Dh. 
Shell elongated, turreted, scalariform; aperture nearly cir- 
cular, dilated, obliquely cut, terminating in front by a semi- 
canaliculated angle; columella slightly concave, cylindrical, 
obliquely truncated, lp simple, and slightly expanded, 
Fossil, 4 species. Hocene. Paris basin. 
[FamMILy APORRHAID#, Gray, 1856,] _ 
Includes the genera APORRHAIS (see p. 244), PTERODONTA, 
STRUTHIOLARIA (p. 246), and Hata; also 
ALARIA, Morris and Lycett, 1854. 
Synonym, Tessarolax, Gabb, 1864. 
Etymology, ala, a wing. 
Examples, Alana “sei Phillips, sp.; A. eae Pictet 
and Roux, sp. 
Shell turreted, fusiform, terminating anteriorly by a canal; 
wing digitated or palmated, formed by the prolongation of the 
free border of the last whorl, and which is applied against the 
last whorl but one, but never adheres to the rest of the spire; 
posterior canal wanting; right lip without a sinus. 
Distribution, about 50 species. Jurassic. Europe, Himalaya 
Mountains, South Africa. Cretaceous, 9 species. England, 
France, Germany. 
The species of this genus haye been referred to Rosiellaria, 
Pierocera, and Aporrhais. 
DIARTHEMA, Piette. 
Shell with continuous varices. 
Distribution. Lower Oolites. France. 
Pelicaria vernis, Adams, has a spiral shejl; the spire of adult 
covered with an enamel coat; aperture ovate; outer lip sinuous, 
sharp-edged. 
P BULIMELLA, Hall, 1857. 
Shell more or less fusiform; whorls convex, the last one much 
enlarged; columella truncated; outer lip thin, with a slight 
notch or sinus at the margin near its junction with the pillar. 
Distribution, 3 species. Carboniferous, Indiana. 
24. 
