OXYSTYLA, SOUTH AMERICAN. 139 



5. ?ulimus undatus APPUN, Unter den Tropen i, p. 141. ?Tno- 

 SCHEL in Schomburgk's Reisen in Britisch-Guiana iii, p. 548. 



Three-banded form. 



Orthalicus zebra SHUTTLEWORTH, Notitiae Malak. i, p. 61, pi. 8, 

 f. 3, 4. PFR., Monogr. iv, p. 588. MOUSSON in Malak. Blatt. xvi, 

 1869, p. 179. Orthalicus ferussaci form B, STREBEL, Beitr. Mex. 

 und Siisswasser-Conch. v, p. 21, pi. 2, f. 1 a-e, 2 a-d, 3 a, b (shells), 

 pi. 9, f. 12, 13, pi. 10, f. 3, 5, pi. 11, f. 6, 6 a (anatomy). Ortalichus 

 tricinctus v. MARTENS in part (all South American references and 

 localities), Biologia, p. 185 (1893). Orthalicus melanochilus, in part 

 (all South American references and localities) FISCHER and CROSSE, 

 Miss. Scient. Mex., Moll., p. 458. 



The literature of this species lias been almost inextricably confused 

 with that relating to 0. ferussaci and its form tricincta. The large ser- 

 ies before me demonstrates the complete intergradation of the striped 

 with the three-banded and Landless forms, and fully supports Strebel's 

 contention that these are only extremes of a variable species, against 

 Dr. von Martens' distribution of them between the two species fer- 

 ussaci and tricincta. 



Numerous specimens before me from Maracaibo and the neighbor- 

 ing island of loas agree with Pfeiflfer's types, as described by him 

 and redescribed and figured by Strebel (pi. 29, fig. 41, type, and figs. 

 40, 42 other specimens from PfeifFer's collection). They are rather 

 livid, faded-out shells, though in quite fresh condition. Sometimes 

 there are no bands on the penultimate whorl, and in some cases there 

 are rather broad markings on the spire, bifurcate above, somewhat 

 as in 0. princeps. 



There also occurs at Maracaibo a form in which the stripes are 

 broad and dark bluish-brown throughout, the surface less wrinkled 

 and less interrupted by vicissitudes of growth (pi. 29, figs. 44, 45). 

 Some of these approach 0. pulchella var. prototypus, but they do not 

 have the brown ground-color of that form, it being nearly white. A 

 wholly similar form occurs at Barcelona. 



Another Maracaibo specimen, pi. 29, fig. 46, somewhat simulates 

 0. pulchella, having numerous thrice angulated flesh-colored stripes 

 on a warm, pale, flesh-white ground. 



On the island of Margarita an ill-defined form occurs (pi. 30, fig. 

 58) with very concave columella, narrow purple-brown stripes obso- 



