2258 ARION CIRCUMSCRIPTUS, 
placed very forward on the shield, which is entire ; mucus pore very distinct, above 
the tail; the young are white or straw coloured, with blackish head and tentacula. 
Habitat : Moist meadows, hedgebanks, ete., common. 
We have found it very uniform and constant in its character, though it may 
possibly be the Avion ater in an immature state. —G. JOHNSTON, Edinb. New Phil. 
Journal, 1828, vol. v., p. 76. 
Description.—ANIMAL of the Arion shape, but stouter especially when contracted 
and with aimueh softer skin than its close ally, Avion hortensis ; about thirty mill. 
in length when adult and fully extended ; of a pale creamy-grey colour, darker 
grey dorsally, but shading to whitish towards the fringe; a black and sharply- 
defined lateral band extends the whole length of the body on each side, beneath 
which is sometimes an indistinct orange band, formed by pigment cells breaking 
throueh the skin; there is a slight mid-dorsal KEEL when young, which, however, 
eradually disappears during growth, but its place is almost invariably indicated by 
a line of pale mid-dorsal TUBERCLES, which contribute to form a pair of dorsal or 
inner bands ; SHIELD granulose and bluntly rounded at both ends, bearing a dis- 
connected continuation of the longitudinal body banding ; BODY TUBERCLES rather 
long and slender ; SOLE opaque, waxy white, and indistinctly tripartite, the median 
portion slightly darker and more transparent than the side areas, and occupying 
more than one-third of the width of the body ; FOOT-FRINGE broad and white or 
pale-grey in colour, usually without perceptible lineolations, but sometimes the 
lineoles are clearly pigmented, especially at the caudal end of the body. 
The SHELL is, as is usual in the genus, represented by a layer of limey-paste, but 
is sometimes found in the form of one or more solid lime particles of variable size. 
INTERNALLY, the SUPRA-CESOPHAGEAL GANGLIA 
are very conspicuous, and united by a slender com- pager 
missure, which, unlike Arion ater, is not opaque-white 
or enlarged medially as in that species. The body 
cavity is whitish and therefore does not display so Y) 
strikingly the exquisite lace-like network of milk- =o 
white arteries and arterioles, a whiteness due to the 
dense investment by lime particles of their outer \ 
sheaths, and which renders them so conspicuous in the IGE Dao Nerve rcentrestan 
dark form of A. afer; the AORTA is large and white, Arion circumscriptus (greatly 
and runs 4 to 5 mill. before its bifureation, the white enlarged). Christchurch, 
investment commences abruptly, as no part of the Hants: 5» Mr. C. Ashford). 
VENTRICLE is white; the OTOCONIA are very numerous, oval in shape, with a 
central speck, and comparatively broader in proportion than those of A. hortensis. 
The CEPHALIC RETRACTORS resemble those of Arion 
hortensis. The broad and flat TENTACULAR muscles 
have their roots four “to five mill. apart to the right 
and left of the kidney, but are not quite symmetrical, \) 
either as to position of roots or width of muscle. 
The branch to the lower tentacle arises at about 
half the total leneth. The PHARYNGEAL retractor ; © 
distinet, and usually dividing about half-way into two 
slender branches, which are fixed to the buccal bulb ; 
the root arises about three mill. behind the kidney, : 
about a millimetre to the right of the median line, and Fic, 233.—Cephalic retractors 
though sometimes broad the muscle is on the whole ai vacant ie 7 
much narrower than the tentacular retractors. C. Ashford). er 
The REPRODUCTIVE ORGANS display an oval or roundish OVOTESTIS, with rela- 
tively large follicles, very dark in colour, especially in the interstices, the whole 
being completely imbedded in the LiveR; the HERMAPHRODITE DUCT is rather 
long and slender, but scarcely sinuous ; ALBUMEN GLAND very large and broad, 
of a dirty semi-transparent yellow; OVISPERMATODUCT thick and very stiffly 
flexed ; OVIDUCT yellowish and very broad ; SPERM DUCT or prostate composed in 
the upper part of small, longish, and somewhat separated follicles ; FREE OVIDUCT 
short, and of uniform width; EPIPHALLUS stiff, and not very slender, gradually 
enlarging downwards, but without the bulbous base of A. hortensis, and shewing the 
internal folds through its substance as white longitudinal lines ; VAS DEFERENS 
rather long ; SPERMATHECA inversely spatulate, the stem short and thickening 
downwards ; ATRIUM very long, somewhat constricted and uniform in width, with 
«1 conspicuous yellow glandular investment, 
