ae 
418 HELICIGONA ARBUSTORUM. 
‘he recent discovery by Mr. Edgar A. Smith that the type specimen 
of Helix rufescens of Pennant is not the species to which that name is 
usually allocated, but is a young shell of /Z. arbustorum, places Pennant’s 
name in the foregomg synonymy, and may unfortunately necessitate 
another name being used for the species hitherto known as //. rw/fescens. 
According to Kuster it is also the Helia castanea of Muhlfeldt. 
This species is now usually placed by systematists in the sub-genus 
Arianta, a group established by Dr. Leach, the name according to the 
Rev. G. A. Frank Knight being based upon that of Ariantas, a king of 
Scythia, who employed arrows to take a census of his people, the name 
therefore probably having reference to the arrow-shaped love-dart of this 
and allied species. The North American species formerly referred to this 
group are simulating forms of more primitive organization. 
Although the description given by Linné (Syst. Nat., ed. xii., 1766) is 
in many respects unsatisfactory, yet his reference to Lister’s figures, the 
presence of specimens in the Linnean Collection now in the possession of 
the Linnean Society, and the acceptance of the identification by his con- 
temporaries and successors, Justify the acceptance of the name. 
Description.—The ANIMAL is usually dark grey or black-brown in colour, vary- 
ing to different shades of grey and brown, and occasionally to a delicate fawn; but 
as in many other species, the colour of the body has no relation to that of the shell; 
there is a slightly paler area along the mid-dorsal line, and the whole body is over- 
spread by thirteen or fourteen oblique = 
forwardly directed rows of distinet < 
tubercles, which, though irregular in 
shape when the body is contracted, be- 
come elongate when the animal is in 
motion ; the DORSAL GROOVES are indis- 
tinet, but the two mid-dorsal rows of 
tubercles are elongate; there are no 
facial grooves, and the lateral groove 
is not perceptible on either side of the 
body ; the MANTLE is said to be reddish- 
brown or dusky, with numerous milk- 
white specks ; FOOT-MARGIN and FOOT- 
SOLE pale greyish tinged with yellow, Fic. 471. — Helicigona aroustorum in motion 
and indistinetly tripartite; TAIL ab- shone the mode of carrying the shell (Photo. 
: Z oy Mr. G. C. Spence). 
ruptly pointed, pale yellowish - grey, 
similarly but more delicately tubereulate than the anterior part of the BODY; 
OMMATOPHORES very long and distinctly bulbous at the end, of a translucent 
yellowish-grey, bat darkened by the presence of the pigmented RETRACTORS, and 
overspread with fine and distant darker granulations ; LOWER TENTACLES semi- 
transparent yellowish-grey, about one-third the length of the upper pair and 
swollen at the tips. 
The shell is carried in various positions when the animal is in motion, sometimes 
vigorously upright, at others almost horizontally. 
The SHELL is usually somewhat globular, but more convex above than below, of 
arich brownish colour, freckled with opaque yellowish or reddish markings, and with 
a single dark brown supra-peripheral band encircling each whorl; the shell is 
strongly and sometimes irregularly seulptured by the lines of growth, and finely 
and closely striate or incised in a spiral direction; EPIDERMIS rather thin, but 
sometimes duplex on the body whorl, the outer layer being usually brown and very 
deciduous ; WHORLS 5-6, convex and without evidence of a keel; SPIRE somewhat 
blunt ; SUTURE rather deep; MOUTH forming about two-thirds of a circle; OUTER LIP 
thick, white and reflected, sometimes strengthened by an internal rib, much 
inflected above and rounded below ; INNER LIP a mere film ; UMBILICUS small and 
oblique, nearly concealed by a fold of the outer lip. 
Diam. 20 mill. ; alt. 16 mill. Average weight of shell 8 grains. 
The EPIPHRAGM is very thin, transparent, and iridescent ; the small ealeareous 
area is opposite the respiratory orifice and close to the outer margin, 
