MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 285 
FAMILY ARIONID# Gray. 
GENUS ARION Feérussac. 
Dr. Simroth suggests that a more satisfactory basis for the classification 
of this group might be afforded by the differences in the length of the 
epiphallus, an organ which seems to possess great constancy in this respect 
in the various species. 
The external markings on the body are directly connected with the 
circulation of the blood, and the lyre-shaped marking on the shield is 
coincident in form with the lung, which lies beneath in the form of a ring. 
As the dark markings on the mantle are dependent on the circulation of 
the blood during the respiratory processes, one may conclude that the 
dark markings on the side-areas are used for skin respiration. This is 
probably, however, less likely in the larger species, on account of their 
thicker skin and greater secretion of coloured slime, so that the correla- 
tion of circulation and markings is not so marked. 
AGOne ater (102). 
Food and Habits.—Young Avion ater are often found on Adium 
ursinum in the neighbourhood of Leipzig. 
Var. aterrima ‘Taylor. 
The name of aterrima has been objected to, as having been previously used by 
Dumont and Mortillet, but this is not so, as those authors do not appear to have 
described any variation under that name. 
Var. castanea Dum. & Mort. 
ENGLAND AND WALES. 
Kent W.—Snub-var. fusco-lutescens, Chislehurst, T. D. A. Cockerell. 
Berks.—Unhill Wood near Streatley, July 1906 ! Rev. E. Peake. 
Anglesey—Sub-var. brannea, common, Cemmaes, July 1895 (C. Oldham, Journ. 
of Conch., July 1898, p. 86). 
Lancashire S.—Sub-var. brunnea, near Oldham (F. Taylor, Journ. of Conch., 
April 1898, p. 49). 
York S.E.—Sub-var. brunnea, Aldborough, T. Petch. 
IRELAND. 
Antrim—The Manse, Antrim, Sept. 1904! W. S. Smith. 
Armagh—Sub-var. brunnea, Forkhill, Jan. 1904, and Armagh, Feb. 1904, P. H. 
Grierson. 
Louth—Sub-var. brunnea, near Carlingford, P. H. Grierson. 
Meath—Sub-var. brunnea, Bective Abbey, March 1905; Moynalty and Kells, 
April 1905, P. H. Grierson. 
Wicklow—Sub-var. brunnea, Greystones, Sept. 1903, P. H. Grierson. 
Galway W.—Dernasligegan, April 1897, R. Welch; this locality is erroneously 
stated to be in East Galway (p. 178). Type and sub-var. brunnea, abundant, 
Gentian Hill, July 1895 (Collier and Standen, J. of Conch., April 1896, p. 178). 
Galway E.—Killinure, Lough Ree, Sept. 1906, R. Standen. 
Clare—Near Limerick, Sept. 1904! G. J. Fogerty. 
Var. plumbea Roebuck. 
ENGLAND. 
Sussex W.—Near Liphook, July 1905, Rev. 8. Spencer Pearce. 
Derby—Rowsley (Lionel E. Adams, Journ. of Conch., vii., p. 77). 
York Mid W.—Addingham, Aug. 1906! F. Booth. Grass Wood, Grassineton, 
Sept. 1906! 8. Hainsworth. 
