185 
Paludina subpurpurea. — Specific character. Penultimate 
longer than the other volutions. 
Paludina suhpurpurea. Disseminator of Useful Knowledgey 
vol. p. 245. 
Desc. Shell subglohular oval, not remarkably thickened y spire 
longer than the aperture, entire at the tip : whorls five, slightly 
wrinkled across, rounded but not very convex ; penultimate volu- 
tion somewhat elongated : suture impressed : aperture ovate- 
orbicular, less than half the length of the shell : labium with cal- 
careous deposite : animal very pale bluish, with minute yellow 
points, particularly on the rostrum, tentacula, and prominent 
respiratory tube, which is as long as the tentacula : eyes on the 
exterior side of the tentacula, near the middle of their length : the 
anterior portion of the foot is very short. 
Ohs. This species was first found by Mr. Lesueur and Dr. 
Troost, in Fox river of the Wabash. In the young state the figure 
is subglobose, and the aperture, although it hardly differs in form 
from that of the adult, is yet longer than the spire. They become 
proportionally more elongated as they advance in age, and the form, 
therefore, of the adult, is so different from that of the young or 
half grown, that in these states it may, very readily, be mistaken 
for a widely distinct species. 
The color of the shell is variable. In some it is pale horn, 
more tinged with yellowish than with green ; in others are traces 
of obsolete purplish bands, in many specimens the whole shell is 
reddish-purple, more or less obscure in different individuals. 
In the autumn it is frequently found between the valves of dead 
Unios, in which it enters perhaps to hybernate. The species is 
certainly allied to the vivipara, but it cannot well be mistaken for 
it, as it is much less dilated, the volutions less convex ; the penul- 
timate volution is much longer in proportion to the length of the 
body whorl, and the umbilicus is obsolete. Plate 30, f. 2. 
Paludina intertexta. — Specific character. Shell with nu- 
merous, minute, transverse, epidermal lines. 
Paludina intertexta, noh. Disseminator of Useful Knowledge, 
vol. 2, y). 244. 
Ohs. In good specimens two or three obsolete, pale bands are 
visible by transmitted light. Plate 30, f. 3, adult shell ; f. 4, old 
specimen ; A, the operculum. 
15 
