ARION ATER. 175 
The A. empiricorum is considered as chiefly West European and to be 
the form inhabiting this country. It is noted as mainly characterized 
by its very short and insignificant lower vestibule and the large and wide 
upper section, an enlargement due to the swollen outlets of the organs 
debouching therein. 
A. ater is said to be confined to North-eastern Europe, and has been 
described as differing by its larger size and in possessing a thick and 
swollen lower vestibule, while the upper section is less noticeable owing 
to the undeveloped state of the oviduct and other outlets. 
These differences are, however, little more than individual, local, or 
seasonal variations in the development of the different organs, as is affirmed 
by Dr. Babor, who shows that the varied development of the atrium is 
merely the expression of sexual phases, while Signor Pollonera has con- 
clusively demonstrated the unreliability and fugitive character of the 
vestibular modifications and their unsuitability for specific differentiation 
in Arion. 
VARIATIONS IN COLOUR OF ANIMAL. 
Var. atra L., Syst. Nat., ed. x., 1758, p. 652. 
The strict type of this species is undoubtedly the black or blackish form, with 
the median area of the foot-sole markedly paler than the side zones. It has, however, 
had a number of special names devoted to it by various observers and is probably :— 
Limax ater L., op. cit. 
Arion empiricorunt aldrovandit Kalenicz., Bull. Mosc., 1851, p. 113. 
Arion rufus B ater Moquin-Tandon, Hist. Moll. France, 1858, ii., p. 10, pl. 1, f. 20. 
Arion (Limax) ater var. niger Dum. & Mort., Moll. Savoie, 1857, p. 6. 
Arion rufus var. nigra Baudon, Journ. de Conch., 1884, p. 196. 
Arion empiricorum var. maurus Held. 
The distribution of this form is almost universal in this country, as it is one of 
the variations more especially evolved by our cool and moist climate. 
On the continent, this form is found in Germany, Holland, Belgium, France, 
North Spain, Portugal, Norway, up to 66° 49’ north latitude, South Sweden, Den- 
mark, Austro-Hungary, Switzerland, and North I[taly. 
. r al 
Var. aterrima ‘Taylor. 
Body, shield, and creeping dise uniformly black. 
It is desirable to discriminate from the ordinary form the jet-black individuals, 
in which the black pigment has also overspread the whole surface of the creeping 
dise. This variety is not common, and would seem to be more especially a northern 
or mountain form, as its occurrence in other places seems to be more or less sporadic 
or casual. Mr. Welch and Mr. Praeger, in Oct. 1897, found some very characteristic 
examples on the summit of Slieve-Donard at an altitude of 2,796 feet. . 
It is not improbable that Avion hispanicus of Simroth, which is characterized by 
its smaller size and uniform black body and creeping disc, belongs to this variety. 
Many authors describe variations of this species as aterrimus totus, but it is not 
by any means clear that the descriptions were intended to apply to the foot-sole as 
well as the body. 
ENGLAND AND WALES. 
Devon N.—Ilfracombe, July 1904! R. Leach. 
Huntingdon—Garden, Huntingdon, Sept. 1904! Miss Emily M. Foster. 
Gloucester E.—Cirencester, Aug. 1904! Mrs. Blundell. 
Merioneth—Hills above Barmouth, alt. 2,000 feet, Aug. 1884! J. Hopkinson. 
Lincoln N.—Rippingale, Sept. 1904! H. Preston. 
Cheshire—Garden, Broad road, Sale, May 1885! C. Oldham. 
Lancashire W.—Over Wyresdale, alt. 1,000 ft., April 1903 ! Rev. W. W. Mason. 
York N.E.—Runswick Bay, June 1885 ! W. Denison Roebuck. 
York Mid W.—Summit of Oughtershaw Moor, Wharfedale, Aug. 1904! W. 
Denison Roebuck. 
Durham—Croft, April 1887 ! and near High Force, June 1884! Baker Hudson. 
Westmorland—On the summit of Coniston Old Man, alt. 2,660 feet, July 1887, 
S. C. Cockerell. Grange-over-Sands, July 1904! W. J. Davey. 
Cumberland—Salkeld Dykes, Penrith, July 1904! H. Britten. Scafell Pikes, 
alt. 3,000 feet ! W. West, 
