Planorllis tumidus, Pfeiffer. — Shell opaque, pale horn-colored 

 or smoky, densely and finely striated, umbilicated above, slightly concave 

 below ; whirls five, convex, sub-carinated on each side, rapidly increasing, 

 separated by a deep suture ; aperture oblique, 

 lunate-rounded, somewhat kidney-shaped. Yig. 178. 



Shell rather large, and somewhat shining, pale 

 horn-colored, or sometimes reddish-brown or green- 

 ish, thick and delicately grooved ; concave and 

 deeply umbilicated in the centre above, as also 

 below, without the well-defined umbilicus, so that 

 the apical whirls are visible ; whirls five or five and 

 a half rapidly increasing, separated by a deep 

 suture, and obsoletelj grooved above and below ; 

 mouth oblique, roundly-lunate and somewhat ob- 

 tusely angular ; columella simple, covered with a 

 thin white callus. Greater diameter of the largest 

 specimen 9 lines, height at the aperture 3 lines. 



Hah. Common at San Juan (Pfeiffer), Havana 

 (de la Sagra), swamps at Vera Cruz and Vamba 

 (Leebmann, Hegewish), Mexico (D'Orbigny). 



Nearly allied to Plan, tenagnphilus, D'Orb. Young 

 specimens resemble a flat form of PI. trivolvis. Planorbis tumidus. 

 Some kindly sent by Prof. Steenstrup, of Copen- 

 hagen, are characterized by stouter, smaller shell, and finer grooves, and 

 also paler color (pi. v, * 1-3) (KUster, I. c). 



Planorbis tumidus, Pfeiffer in Wiegm. Archiv. 1839, 354 ; in Kiister, Ch. 

 ed. 2, p. 39, pi. vii, f. 10-12 ; pi. ix, f. 1-3. 



Planorbis caribseus, Orbigny, Sagra's Cuba, 193, pi. siii, f. 17-19. 



Planorbis intermedins, Philippi, Conch. Cab. I, tab. i, 17, 16, f. 18, 19. 

 Var. fig. malac. an. Plan, captlluris, Beck ? Ind. p. 110. 



Guatemala : Rev. H. B. Tristam. The description and figures 

 given above are copied from Chemnitz, ed. 2. 



