29 



PLANORBIS ALBUS, Midler, 



Plate 4.— Figs. 8—10. 



P. testa pallida, tenui, hirsuta, utrinque anguste in medio 

 excavata: anfractibus 4 rotundatis, lineis revolventibus his- 

 pidis. 



SYNONYMS AND REFERENCES. 



P. ALBUS, MiJLLER. Verm. ii. 164. 



P. mspiDUS, Drap., p. 43, pi. 1, figs. 45—48. 



" " Lamarck. An. sans vert., vol. 8, p. 387. 



P. HIRSUTUS, Gould. Invert, of Mass., p. 206, fig. 135. 



DESCRIPTION. 



Animal dark reddish-brown, with a hght hne 

 running back from the posterior base of the 

 tentacles, central line of these, dark: eyes dis- 

 tinct black points, at the antero-internal base of 

 the tentacles. 



Shell pale, fragile, composed of four inflated, 

 compact, circular whirls, equally convex on both 

 sides, marked by numerous hispid, revolving 

 lines, which are covered with deciduous bristles: 

 each side with a nearly similar, deep, and rather 

 narrow excavation: aperture oblique, nearly cir- 

 cular. 



