185 



Paludina subpurpurea. — Specific character. Penultimate 

 longer than the other volutions. 



Paludina subpurpurea. Disseminator of Useful Knowledge, 

 vol. 2, p. 245. 



Desc. Shell subglobular oval, not remarkably thickened ;'^ 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 diifers 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 diflferent 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 i.« 

 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 body whorl, and the umbilicus is obsolete.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, nob. Disseminator of Useful Knowledge, 

 vol. 2, p. 244. 



Obs. 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 



