34 SIMROTH : ON MIMICRY OF CLAUSILIA. 



with six curved transverse lines, as if there were seven whorls without 

 the little ones of the straight upper end. The mouth was narrowed 

 as in Clausula. Every stripe was composed of two lines, a darker 

 and a clearer whitish one, giving one the impression of a Clausilia, 

 whose sutures were filled up with powdery limestone as is usual in 

 these localities. 



The latero-ventral view (Fig. C) is entirely different, the transverse 

 lines being restricted to the dorsal side. The tail-end is compressed 

 and curved downwards ; being narrow when looked at dorsally but 

 considerably larger when seen laterally ; for there are two flaps with a 

 slit between them for the exit of the perfect insect after metamorphosis. 



I think it is clear that the whole arrangement is very effective and 

 Hkely to deceive small birds frequenting the rocks for feeding upon 

 insects. Larger birds, such as pigeons for instance, would take shells 

 such as Clausula, but not so the Si/lvlae, Turdldae and others, preferring 

 the objects in question. 



A Coleophoride Lepidopteron imitating Clausilia. A. Natural size. B. Dorsal 

 view enlarged. C. Lateral view. 



Although it is clear that this mimetic character is of protective 

 value to the larvae, it is very difficult to account for its origin. When 

 the larva enlarges its case, does its build circle after circle by its sali- 

 vary glands, in the manner the silkworm forms its cocoon? If so, we 

 could understand the darker rings as being added at varying intervals. 

 The explanation of the interruption of the rings on the ventral side is 

 more difficult. I think before we attempt to explain the growth, etc., 

 of this interesting structure, we must first investigate the manner in 

 which the larva produces it. Probably it is not in the same manner as 

 that which takes place in the formation of the cocoon in the silkworm. 



