366 CONCHOLOGICAL AND ENTOMOLOGICAL NOTES. 



CONCHOLOGICAL NOTES. 



Bulimus acutus. — I observe, in conchological notices in number for 

 present month, that Bidinms acuttts is noted for Co.'s Down and Donegal, the 

 intervening county (Antrim) being left out, It is, however, found in several places 

 in Antrim, and noted in Thompson's 'Natural History of Ireland.' — S. A.Strwart, 

 6, North Street, Belfast, 3rd December, 1884. 



Amalia gagates in North Lincolnshire. — I have to chronicle an 



additional county for this interesting but imperfectly understood species. Among 

 some slugs obligingly sent by Mr. J. Eardley Mason, of the Sycamores, Alford, 

 and which were collected by his sons in the garden there, were a couple of examples, 

 one adult, the other very young, of the var, pbi77ibca of this species. On com- 

 municating with Mr. ]Mason he sent some more specimens, one of them of the same 

 variety, but the other w^as of the typical form, and particularly interesting to me 

 because — although I have seen scores of the var. pliDubea from numerous British 

 and foreign localities — I had never before seen an example which could be referred 

 to the type, defined as being black on the back. Writing this note reminds me 

 that this species appears, from the observations of Mr. Taylor and myself, to be 

 by no means so rare an animal as the text-books would lead one to suppose. Many 

 conchologists are, however, unable to discriminate it from the otlier British keeled 

 slug, Amalia niarginata, though the differences are obvious enough with a little 

 attention. Why has it not yet been found in Yorkshire ? It occurs plentifully in 

 county Durham, and, as we now know, in North Lincolnshire. — W. Denison 

 Roebuck, Leeds, September 12th, 1885. 



ENTOMOLOGICAL NOTE. 

 The process of skin- casting in a Lepidopterous larva.— 



The following account of a larva casting its skin may be of interest, and may also 

 throw some light on the curious phenomenon of ' moulting,' for in many works on 

 entomology we are only told that ' the skin breaks at the back near the head, and 

 that the larva walks out of its skin after a due amount of twitching and wriggling.' 

 Whilst examining a looper caterpillar, about % inch long and very transparent, 

 under the microscope, I was veiy much struck with a peculiar internal movement — 

 each separate segment, commencing at the head, elongated within the outer skin 

 W'hilst the next ones remained in their former state. Each segment in its turn 

 behaved in this curious manner until the last w^as reached, when the motion was 

 reversed and proceeded towards the head, when it was again reversed. I only 

 saw this process of elongation accomplished three times, although it may have 

 been going on for some time before I captured the caterpillar, which I found in a 

 quiescent state. The whole proceeding appeared as if the larva was gliding 

 within itself, segment after segment, the outer skin remaining stationaiy as if held 

 by the other segments, whilst the particular one in motion freed itself within. 

 After remaining motionless for a short interval the skin near the head swelled and 

 burst open at the back ; then I became aware of the fact that the curious process 

 of ' moulting ' was going on before my eyes. Presently out comes the head of the 

 new caterpillar, pushing forward the old one ; looking wonderfully clean with its 

 ten shining black eyes on a cream coloured ground. After a short struggle the 

 new tme legs, transparent fleshy limbs, very much resembling those of a newly- 

 hatched spider, appear, pushing off and treading under foot the old ones. The 

 outer skin must have suddenly contracted, and although I did not see the actual 

 process of contracting, I conclude such was the case, for on examining the 

 latter segments, there I found the skin and the old true legs shrivelled up. The 

 larva then, by a series of wild wriggles, endeavoured to extricate its new prolegs 

 (false legs), which in a short time it accomplished. Then all is clear, and the 

 larva, which is quite exhausted, coils itself up and literally pants* for breath. 

 W^hen it has ^ got its wind,' it wanders off probably in search of the food which it has 

 well earned. I have no doubt that such is the process with all larvae, although 

 the internal movements of most, especially those having thick and opaque skins, 

 cannot be so easily watched as the young and more transparent ones. — Edward 



HOWGATE, Water Hall, Mirfield, i6th September, 1885. 



Naturalist, 



