142 MOLLUSCA. 
H. griseola. In others, again, the bands are very pale, rather pellucid than brown, and 
visible only by close inspection. ‘The thickness of the shell, the elevation of the spire, 
and the constriction behind the aperture exhibit also gradual differences, each inde- 
pendently from the other; the constriction exists ordinarily only in the lower half of 
the whorl, and is there as distinct in many specimens of H. griseola as in the typical 
Hf, berlandieriana. The smallest specimen which I have seen (fig. 13) measures 
74 millim. in diameter and 63 in height; it exhibits the more conoidal-globose figure of 
H. berlandieriana, but has brown bands on the upper and lower face as in H. griseola. 
Our fig. 14 is taken from an unusually flat specimen, but otherwise agreeing 
with typical H. berlandieriana; fig 17 represents the var. griscola not full-grown, of a 
pellucid greyish colour, nearly without white. 
Helix berlanderiana (sic), Pfr. Monogr. Helic. Vivent. i. p. 165= H. virginalis (Jan), 
ibid. tii. p. 132, and vii. p. 238, seems to be, according to the description, a very diffe- 
rent shell, belonging to Xerophila—* testa umbilicata, depressa; peristoma acutum, 
intus labiatum,”—and probably not really from Texas. A friend of Jan, Villa (Dispos. 
Syst. Conch. 1841, p. 12), says that H. wirginalis, Jan, is from Sicily.. 
Subgen. Arionta, Leach. 
Shell globose, of moderate or rather large size, perforated, striated, often one-banded ; 
peristome thickened and distinctly reflexed. Jaw with a few stout ribs. Two long and 
simple glandule mucose; receptaculum seminis (genital bladder) with a long filiform 
appendage. Dart in shape of a spade, two-edged, thickened at the base. 
The very characteristic form of the dart of the type of this subgenus, Helix arbus- 
torum, L. (see Ad. Schmidt, in Zeitschr. fiir Malak. 1850, t. 1. fig. 8), is seen also in 
the North-American H. mormonum, Binney (Terr. air-breath. Moll. N. Am. v. t..13. 
fig. F). 
Leach’s original spelling is “ Arianta;” but as this name is derived etymologically, 
without doubt, from the Greek Arion, a sort of snail mentioned by lian (De Natura 
animalium, x. 5), the spelling ““Arionta ” is preferable. 
For Table of Species, see page 139. 
16. Helix flavescens. (Tab. VII. figg. 18, 18 a-e.) 
Helix flavescens (Wiegm. in Mus. Berol.), Pfr. Monogr. Helic. Vivent. i. p. 337 (1848); in Mar- 
tini & Chemnitz, Syst. Conch.-Cab. ed. 2, Helix, ii. p. 238. no. 704, t. 112. figg. 14, 157; 
Malak. Blatt. iii. p. 231 (1856) *. 
Helix (Arianta) fiavescens (Wiegm.), v. Mart. in Malak. Blatt. xii. p. 18 (1865) *. 
Helix (Praticola) flavescens (Wiegm.), v. Mart. in Jahrb. Malak. Ges. vii. p. 96, footnote (1880) *. 
Helix (Leptarionta) flavescens (Wiegm.), Fisch. & Crosse, Miss. Scient. Mex., Mollusca, i. p. 255°. 
Hygromia fiavescens, H. & A. Adams, Gen. Moll. ii. p. 2147. 
Praticola flavescens (Wiegm.), Strebel, Beitr. Mex. Land- und Sussw. ~Conch. iv. P- 4], t 13. 
fig. 18°. 
