DRYM^EUS, MEXICO AND CENTRAL AMERICA. 87 



Aperture ovate, banded inside, oblique ; peristome thin, not ex- 

 panded, the columellar margin. triangularly reflexed above ; columella 

 straight or with a low convex fold above. Alt. 20, diam. 11, length 

 of aperture 9-10 mill. 



JV. Guatemala: Panzos (Conradt). Central Guatemala: San 

 Geronimo, near Salama (Champion); vicinity of Guatemala City 

 (Stoll). Central Costa Rica: San Jose (Pittier); La Uruca, near 

 San Jose, at an elevation of 100 metres above the sea, under dry 

 leaves (Biolley); Alajuela (Orosco). S.Panama: hla del Rey (San 

 Miguel) in the Pearl Islands, and Taboga Island* both in the Bay of 

 Panama (coll. Cuming). 



Bulinus vexillum BRODERIP, P. Z. S., 1832, p. 105. SOWERBY, 

 Conch. Illustr., Bulinus, fig. 26. Bulimus vexillum DESHAYES, in 

 Lamarck, Hist, des Anim. sans Vert., ed. 2, viii, p. 272. REEVE, 

 Conch. Icon, v, Bulimus, pi. 23, fig. 152 (not of Wood, 1828). 



Bulimus (Bidimtdus) alternans BECK, Index Moll. p. 65 (1837) 



Bulimus alternans PFR., Monogr. Helic. Vivent. ii, p. 207. Bulimus 

 (Leptomerus) alternans ALBERS, Die Helic. ed. 1, p. 166. PFR., in 

 Malak. Blatt. ii, p. 160 (1855) Orthalicus (Leptomerus} alternans 

 H. & A. ADAMS, Gen. Rec. Moll, ii, p. 156. Bulimulus (Liostracus) 



alternans v. MART., in Albers' Die Helic., ed. 2, p. 213 BINNEY, 



Ann. Lye. Nat. Hist, of N. Y., x, p. 305 (jaw and radula) FISCH. 

 & CROSSE, Miss. Scient. Mex., Mollusca, i. p. 500, pi. 23, fig. 5. 

 O. STOLL, Guatem. Reisen. p. 33. Liostracus alternans W. G. 



BINNEY, Ann. N. Y. Acad. Sci. iii, p. 122 (jaw and radula) B* 



alternatus FORBES, P. Z. S., 1850, p. 54 (not of Say). 



More allied to the thin, banded species of Colombia, Trinidad, 

 etc., than to any of the preceding Mexican species. The number of 

 bands is constantly five, in the series before me, but they vary in 

 width. Usually the fourth band is wider than those above, and the 

 second band narrow ; but in some shells the second band is wide, 

 and the third reduced. Von Martens writes : 



" Dr. O. Stoll has observed this species upon a shrub, Baccharis 

 salicifolia, in company with 0. jonasi but much less frequent. Dur- 

 ing the dry season it conceals itself beneath stones and amongst the 

 roots of the above-mentioned shrub, more rarely on its branches, and 

 closes the aperture with a thin transparent epiphragma ; in this state 

 it often becomes the prey of the rapacious Glandina aurata, which 

 does not ascend the shrubs. He mentions also that full-grown spe- 



