MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 
i 
ys 
=I 
Arion circumscriptus Johnston. 
1819 Arion hortensis var. a and 8 Férussac, Hist. Moll., pl. 2, f. 6, and pl. SA, ff. 2-4. 
1828 — circumscriptus Johnston, Edinburgh New Philos. Journ., v., p. 76. 
1837 — marginatus Kickx, Bull. Acad. Roy. Soc. Bruxelles, iv., p. 139. 
1852 . — leucopheus Normand, Descr. Six Limac. Nouvy., p. 6. 
1864 — hortensis var. grisea Bourguignat, Malac. Gr. Chartr., pl. 1, f. 9-11. 
1868 — bourgwignati Mabille, Rev. et Mag. Zool., xx., p. 138. 
1868 — neustriacus Mabille, op. cit. ; 
1885 — (Carinella) bourguignati Pollonera, Moll. Terr. Piemonte, p. 28. 
1887 — _ celticus Pollonera, Spee. Nuov. Arion Europei, p. 19, ff 11, 22, 33, 37. 
1887 — _ nilssoni Pollonera, op. cit., p. 19, ff. 33-34. 
1889 — ambiguus Pollonera, Nuove Contr. Arion Enropei, p. 15, ff 16-19. 
1890 — subcarinatus Pollonera, Recensem. Arionidie Paléarect., p. 27. 
1822 Limax fasciatus Y Nilsson, Hist. Moll. Sveciae, p. 4. 
1868 Prolepis hortensis Malm, Limae. Seand., ple2etao: 
1881 Geomalacus bourguignati Locard, Moll. Ain, p. 11. 
ISTORY. — Arion circumscriptus 
(circum, around; scriptum, marked) 
in allusion to the distinct lateral black 
zone almost encircling the body, is here 
associated with the late Dr. G. Johnston, 
of Berwick, the author of the excellent 
work, an ‘ Introduction to Conchology,’ 
who first differentiated and named the 
species. It is also probably the Arzon 
hortensis vars. « and Pb of Férussac and 
the Limux fasciatus var. y of Nilsson, 
and is said by Pollonera to be the same 
as Geomalacus bayani Jousseaume and 
Arion dupuyanus of Bourgmgnat, but 
the latter species is described as possess- 
ing a strong keel and yellowish foot, 
characters which are somewhat against 
this allocation. 
The sub-genus Curinella has been 
instituted by Mabille for the reception 
of the present species and closely-allied 
forms, a grouping based upon the pos- 
session of a dorsal keel during the earlier 
‘ stages of growth, but which may occasion- 
ally persist to adult life. 
Diagnosis.—Arion circumscriptus is larger, broader, and far paler in 
colour than A. hortensis, the species with which it has been so long con- 
founded. The distinctly white foot of the present species is also one of its 
most striking characteristics. 
INTERNALLY, it is distinctly separated from its ally, Avvon hortensis, by 
its very elongate and narrow ATRIUM, pointed SPERMATIIECA, slender and 
rather uniform EPIPHALLUS, and shorter FREE OVIDUCT. 
Original Description. — Arion circumscriptus. Body greyish-black, spotted, 
with a black fascia round the shield and body, the respiratory aperture anterior, | 
Body, 1 or 14 inch long, not keeled, nor much narrowed at the tail ; greyish- 
black, marbled, with a narrow fascia surrounding the back and shield ; sides bluish- 
erey ; foot white, opaque; tentacula rather short, biack ; respiratory aperture 
