368 JOURNAL OF CONCHOLOGY, VOL. 9, NO. 12, OCTOBER, I9OO. 



I never noted any young ones amongst the few I saw in that month, 

 but in November immature specimens were decidedly in the majority. 

 The five banded form occurred to the extent of about 25 per cent, of 

 of the total specimens. Curiously enough I could never find this 

 species on the Spanish mainland near Gibraltar. 



H. lactea Mull. — With the doubtful exception of H. marmorata 

 this is perhaps the commonest terrestrial mollusc which Gibraltar 

 produces, for except right in the town it is common everywhere, but 

 much more so on the western face of the Rock than the other. It 

 has a habit peculiar to it and to H. virgata, H. pisana, and to a less 

 extent to If. marmorata, of fixing itself in some exposed position in 

 the full glare of the sun and waiting there till the heavy night dew 

 commences to fall, when it proceeds to feed. In wet weather, how- 

 ever, it prowls around in search of something to eat in the daytime. 

 It may be as well to mention here the fact that this species, in common 

 with H. marmot ata, Rumina decollata and Hyalinia draparnaldi 

 suffers severely from the attacks of certain parasitic diptera and 

 coleoptera. I have frequently found specimens of the above 

 species, from the mouths of whose shells was trickling a thick, black 

 slimy material; such shells are often found to contain as many as 

 twenty or thirty dipterous pupae. Again I have frequently taken 

 Rumina decollata with almost all the whorls filled up by a big white 

 coleopterous larvae. I was at first of opinion that these larvae had 

 only attacked the molluscs after death, but later I had the good 

 fortune to observe a coleopterous larva attacking a living, immature 

 H. marmorata, and this larva I kept until it became a perfect insect, 

 one of the Drilidae. There can be no doubt from the differences in 

 size of the larvae, and from the fact that my specimen completed its 

 metamorphosis in a comparatively young H. marmorata, that the 

 larger ones are those of a different species. 



The Gibraltar specimens, though nicely marked, are not very large, 

 but here again there is a good deal of difference between those from 

 the limestone near the top of the rock and those from the meta- 

 morphic deposits at its base — the former are far more solid and rather 

 smaller than the latter, and as a rule less brightly marked. I found 

 this shell numerous both at Algerciras and Eonda, on the Spanish 

 mainland, where, however, the specimens are smaller than they are in 

 Gibraltar. 



Var. alybensis. — This variety, named by Kobelt, is still the 

 commonest form at Gibraltar. 



Var. maura. — Occurs sparingly at Gibraltar and more plenti- 

 fully at Ronda, a town about eighty miles inland from Gibraltar. 



Var. grisea. — A curious point about this variety is the fact that 

 whilst in the autumn of 1898 it only formed about five per cent, of all 



