CONCHOLOGY. lil 
M. Sayii.* M. plicata.* 
M. elevata.* M. inflata.* 
M. armigera.* N. conica.* 
M. multilineata.* M. catenaria.* 
M. proxima* M. simplex. * 
M. Hydeii.* M. excurta.* 
M. salebrosa.* ! M. annulifera.* 
M. bitaeniata.* M. pyrenella.* 
N. lema.* M. coma.* 
M. nassula.* M. alveare.* 
M. trochiformis.* M. cylindracea.* 
M. elevata.* M. vestita.* 
M. laqueata.* M. caniculata.* 
M. semicarinata.* M. Virginica.* 
M. subularis* (Lea). M. tuberculata* (Lea). 
'M. acuta.* oe M. elongata.* ss 
2. Genus Pirena. PI. X. 
Animal. Much elongated, mantle prolonged into a canal at 
the left side, but without distinct tube ; foot short, oval, with an 
anterior marginal furrow; head terminated by a depressed pro- 
boscidiform muzzle; tentacula very distant, thickly annulated, 
dilated in the inferior half of their length, and having the eyes at 
the summit of this dilation; mouth a terminal and vertical slit, 
without labial tooth, and with a very small tongue; a single long 
and narrow branchia. 
Shell. Distinguished from the preceding genus by having a 
sinus at the base, and another at the summit; turreted ; aperture 
longitudinal, right lip sharp, base of the columella inclined to the 
right. Inhabits the rivers of India and Africa. One species is 
found in America. Six species. ’ 
Pirena terebralis. Pirena aurita. 
P. cancellata. P. spinosa. 
P. granulosa. 
~ P. scalariformis.* 
3. Genus Melanopsis. Ph. X. 
Animal. As preceding genus. 
