110 AGRIOLIMAX AGRESTIS. 



Protective Resemblance. — Pew observations have been made with 

 respect to the protection this species may derive from simulating other 

 animate or inanimate objects, but it has been suggested that there is a 

 striking resemblance between this animal and the bloom-sheaths of the 

 black poplar {Populus nigra), and also that the pale forms show a marked 

 approximation in appearance to the cocoons of the Burnet moth {Zygwna 

 fiUpendulcB), this approximation being so close that at a short distance the 

 resemblance seems complete; these, however, are probably only accidental 

 cases of similarity, and can scarcely be compared with the remarkable 

 examples of protective resemblance due to natural selection. 



Parasites and Enemies. — Though the enemies of this species are 

 very numerous, its enormous fecundity enables it under ordinary conditions 

 not only to maintain its ground, but to increase in numbers. 



j\I. Barthelmy affirms that a minute Nematode worm (Ascarioides limacis) 

 is found even within the egg ; while M. Laurent claimed to have detected a 

 minute parasitic fungus therein, even before exclusion from the parent slug. 



The active Trichomonas limacis Duj., and the rotifer Albertia vermicu- 

 laris are found within the intestinal canal of adults, and the hair-worm 

 (Alennis nigrescens) in the body cavity, while at one time A. agrestis was 

 regarded as the most probable medium through which the dreaded scourge 

 Distomum, hepaticum was conveyed to sheep and other ruminants. 



Ducks, rooks, pheasants, quail, etc., feed eagerly upon A. agrestis, a food 

 to which the fieldfare also seems particularly partial. 



They are favourite morsels with the hedgehog, which often scratches them 

 out from the crevices or from the roots of grass where they are concealed ; 

 while the Blindworm {Anguis fragilis) is said to prefer this slug to any 

 other food, and in captivity will take four or five or even more at a meal. 



Fossil. — Agriolimax agrestis has been recorded in the fossil state from 

 many localities, and from many of the deposits belonging to the Post- 

 Tertiary periods, but as the specific characters are not sharply defined on 

 the vestigial shell, the identifications probably cannot in every case be 

 implicitly relied on. 



Pliocene. — Mr. J. C. Mansel-Pleydell reports it as a Pliocene fossil from 

 Dorset, but it is not included by Kennard & Woodward amongst the 

 Pliocene fossils of the south of England. 



Pleistocene. — Kennard & Woodward record it from Fisherton, in Wilt- 

 shire, and also from Portland, Dorset, the specimens from the latter locality 

 having been identified by Dr. Jeffreys. In Sussex, Mr. ,J. P. Johnson 

 found it in deposits on the foreshore at West Wittering. In Kent, Ken- 

 nard & Woodward chronicle its presence in the Ightham fissure, in the 

 Happaway Cavern, at Swanscombe, Crayford, and Erith; while the Rev. 

 R. Ashington BuUen records it from a pre-neolithic chalky-loam deposit 

 on the Barton Court estate, Buckland, near Dover. In Essex, Mr. J. P. 

 Johnson has found it in the Uphall brickyard, Ilford, and Mr. Miller 

 Christy reports it as common in the Camm Valley alluvium at Chignal; 

 it has been reported from Copford, and also occurs in the Palaeolithic river 

 drift at Grays, from which place it was formerly recorded as Lima.r soirerhyi. 

 Kennard & Woodward state, on the authority of Dr. Jeffreys, that it has 

 been found between Upton and Chilton, in Berkshire; and Mi-s. Mclienny 

 Hughes reports it from the deposits at Barnwell Abbey, Cambridgeshire; 

 Sandberger (Vorwolt, p. 75.5) vouches for its occurrence in this country 



