HELIX. 157 
H. altispira approaches the polymorphous Z. trigonostoma, but considerably exceeds 
in height its var. elevato-conica, from which it also differs in colour. 
25. Helix zhorquinensis. 
Helix (Oxychona) zhorquinensis, Angas, P. Z.S. 1879, p. 475, t. 40. fig. 17. 
Hab. Costa Rica: along the Zhorquin river (Gadd 4). 
“Animal very slender, nearly white, pale brownish on head and top of body” 
(Gabb) }. 
This fine species, by its exact conical form, sharp keel, and the outward projection 
of the aperture, approaches very remarkably the well-known Brazilian H. difasciata, 
Burrow, and HH. lonchostoma, Menke. On the other hand, the “ very slender” animal 
confirms its affinity with H. trigonostoma. 
26. Helix bicincta. 
Helix bicincta, Pfr. Symb. Hist. Helic. i. p. 38"; in Philippi’s Abbild. neuer Conch. i. p. 49, t. 8. 
fig. 5°; Monogr. Helic. Vivent. i. p. 841°, and v. p. 352‘; in Martini & Chemnitz, Syst. 
Conch.-Cab. ed. 2, Heliz, ii. p. 364. no. 894, t. 138. figg. 13, 14°; v. Mart. in Malak. Blatt. 
xil. p. 17 (1865) °. 
Helix (Leptarionta) bicincta (Pfr.), Fisch. & Crosse, Miss. Scient. Mex., Mollusca, i. p. 253, t. 10. 
fig. 7". , 
Corasia bicincta (Pfr.), Strebel, Beitr. Mex. Land- und Siissw.-Conch. iv. p. 51, t. 18. fig. 17 (young 
shell) °. 
Hab. S.W. Mexico: State of Oaxaca (Hegewisch 1°); Oaxaca (Uhde®); Juquila and 
Panistlahuaca, in the same State (Boucard 4~‘). 
E. Mexico: Soledad, between Cordova and Orizaba (Hége). 
Variable in size and colour. The largest specimen I have seen, from Soledad, 
measures 19 millim. in diameter and 13 millim. in height; the smallest, full-grown, 
15 and 104. The colour is dull greyish-chocolate above and below or pale brimstone- 
yellow on both sides, or the upper side pale greyish brown and the lower side whitish, 
or greyish-white above and below; the dark brown band in the periphery is wanting 
only in some whitish specimens ; the opaque white or pale yellow sutural zone and the 
peripherical well-defined band of the same colour immediately beneath the dark one are 
always present; a dark brown or blackish transverse band close behind the white 
aperture is visible in all the specimens, white as well as brown ones. In adult examples 
the umbilicus is either nearly or quite closed by the large reflexed columellar margin 
of the aperture. HH. bicincta, in well-preserved condition, is one of the handsomest 
species of the genus in Mexico. 
