THE CONCHOLOGIST. 



35 



resemble the var. subalbida, but are 

 smaller ; slightly keeled ; sides, bluish- 

 grey, instead of white; margin, not lineo- 

 late : slime, not coloured. In alcohol 

 the sole, which was bluish or greyish- 

 white, became decidedly yellowish, but 

 it may have been stained by the slime 

 of an ./. hortensis in the same bottle, 

 which had turned the alcohol yellow. 



Form, subalbida, Ckll., Brit. Nat, 1891, 

 p. 1 01. Size and shape of boi/rgiiignati, 

 but no keel ; head and tentacles grey ; 

 sides below bands, opaque white ; bands 

 as in hotcrguignati : area between bands, 

 dark grey on back, pale grey on mantle, 

 darkest in median line — i.e., with a dark 

 broad dorsal band, then a paler grey 

 sub-dorsal area, and then the dark 

 lateral bands ; neck, grey above ; respi- 

 ratory orifice white margined ; sole, 

 white ; the white of the sole and sides 

 is really a creamy-white — i.e., with a 

 yellowish tint, especially sides of sole. 

 The general colouring is like A. ater 

 {empiricoriim) var. albolateralis, but the 

 margin is not orange ; margin with 

 slight grey marks at intervals, but no 

 lineoles ; mucus pore equilaterally trian- 

 gular, well-formed ; slime not coloured. 

 One specimen at Bailey Gate, Dorset. 



The above description was made from 

 the living slug ; after it was in alcohol 

 I made the following notes : — 



Length (in alcohol) 13, lat. 3^ ; mantle 

 long, 5 mill. ; respiratory orifice, 2 mill, 

 from anterior border of mantle ; sole, 

 lat. 3 J- mill. ; sole, slightly transversely 

 grooved laterally, no distinct areas ; sole- 

 edge not dark-lineolate, but sides of 

 body with a line parallel to sole, where 

 the sulci bc'.id downwards, simulating a 

 lineolate sole-edge ; mantle truncate 

 anteriorly, rounded behind ; no keel on 



body ; reticulations elongate ; tail bluntly 

 rounded. In s|)irit, under the same 

 conditions as the var. aruioricana 

 recorded above, the sole and sides 

 turned pale primrose yellow. 



It is difticult to find good characters 

 to separate these slugs grouped under 

 circimiscriptiis. In the forms referred 

 to CDubigmts the keel is practically 

 obsolete, and what is more important, 

 there is no sort of pale dorsal line. 

 Tlie sole, also, in the living slug is not 

 of the same dead-white colour as in 

 bourgtiigiiaii, but is more inclined to 

 creamy or greyish. In all these respects 

 the characters of A. hortensis are 

 approached, and yet the whole build or 

 " facies " of the slug is so essentially 

 that of circuDiscriptiis that it need not 

 be confounded with ho'tensis, even on 

 the most superficial examination. It 

 seems especially important that living 

 slugs in this group shr.aild be studied, 

 as the keel and sole characters are 

 deceptive at times in alcohol. For 

 separating bouri^iiignafi from aiiibigmis, 

 it is also desirable to have some young 

 examples, as old specimens of true 

 bourguigna/i, especially when in alcohol, 

 do not show any keel. I think the 

 young of true boufgiiignili has ahoajs 

 at least some trace of the pale dorsal 

 line, even in alcohol. 



I.NSTiTUi'K OK Jam.mca : KiNcsroN, Jamaica. 

 August \2th, 1S91. 



