COCKERELL AND COLLIXGE : CHECK-LIST OF SLUGS. 29 



and New Caledonia, which appear to be veritable raroton- 

 gafius* but are not, so far as I can judge, the same as 

 Icevis. The Rarotonga slug looks like agrestis, but one of 

 the New Caledonia ones has the ground-colour dark, as in 

 canipestris. Without dissection it would be very diiificult to 

 make any positive assertion about their identity, but it 

 seems possible that they may represent a distinct species. 

 170. A. qiieenslandiciis. According to Dr. Simroth this is Icevis. 

 166 f. ttigrescens. Merely a mutation; dark, blackish or brownish- 

 grey, mantle mottled with darker, back obscurely mottled, 

 tentacles blackish, central area of sole darker than lateral 

 areas. Washington, D.C., several examples (Dr. R. E. C. 

 Stearns). 

 179-188. The species oi Parma cell a doubtless ought to be reduced, 

 but it seems best to consider them distinct until they are 

 definitely proved otherwise. Simroth in his work on the 

 slugs of Portugal and the Azores, gives an interesting 

 discussion of the matter, and concludes that valeiiciermii, 

 des/iayesi, calyculata, caliosa, and dorsalis are all races of 

 olivieri ; which is, in fact, the only valid species of 

 Parmacella ! ' 



The curious thing is, as Simroth points out, that whereas 

 there is considerable difference of colour among the so-called 

 species, tho.se from the extreme east most resemble in this 

 respect those of the extreme south-west. 



I made a comparison of certain specimens in the British 

 Museum, and found therein structural differences which 

 may help to distinguish the species. The reticulation is 

 not equally fine in all, and in order to test this point, 

 I counted the transverse lines or grooves extending from 

 mantle to foot in lo millim. of the length of the slug. 



P. olivieri from the Caucasus showed 5 lines in 10 mm. 



P. V. maculata from Gibraltar showed 7 lines in 10 mm. 



P. gervaisii iwm Gibraltar showed 7 lines in 10 mm. 



P. des/iayesii from Gran showed 11 lines in 10 mm. 



Of course these measurements are from specimens in 

 alcohol. 



* I made the following descriptive notes from these : — 



(i). Rarotonga slug. lo mm. long (in alch.); ochreous, body almost unicolourous, 

 mantle dark. Respiratory orifice pale-margined. .Medium area of sole 7'ery 

 little wider than either lateral area. Hardly any keel. Structure like a^esth: 



(2). New Caledonia slug. i6 mm. long (in alch.); mantle 71 mm. long blackish or 

 black, paler at sides, margin of respiratory orifice paler. Body rather well but 

 obtusely keeled, very dark-blackish above, the reticulations marked black, more 

 or less. Sole yellowish-grey, unicolorous, median area a little wider than either 

 lateral. Ground colour dark, but structure like agrestis. 



(3). New Caledonia slug. Differs from 2, in having ground-colour lighter. 



