MIMICRY AMOXGST THE BLATTID.E. 363 



Fletcher, who has watolied this insect in a state of nature in 

 C!eyh)n, tells me that when it is flying it looks very like a con- 

 spicuous Agaristid moth, Mimeusemia ceyloiiica Hmpsn. The 

 resemblance is certainly not veiy striking when the dried insects 

 are seen side by side in a cabinet, but no tield-natura.list will 

 iittach very much importance to that, and in any case Mr. Fletcher 

 does not maintain that the resemblance is detailed and accurate, 

 but merely geneiulised. 



The power which the females of species of Perisphaeria and 

 Pseudoylomeris have of rolling themselves up into spherical balls 

 when alarmed is well known, and on account of their convex 

 form and black shining colour, they undoubtedly bear an ex- 

 tremely close resemblance to the pill-millipedes which ai'e so 

 abundant in the tropics. But here again I doubt if any parti- 

 culiir species of millipedes are copied. It is certainly a fact that 

 whilst two species of Perisphaeria were not infrequently met with 

 in Sai'iiwak, both I'ather small, black species, I never once found 

 a milli})ede corresponding in size or colour to them. It is by no 

 means certain that the pill-millipedes are distasteful animals — on 

 the contrary, it is quite probable that they ai'e palatable but well 

 protected by their hard integuments and power of rolling up into 

 a, ball. The same habit is shown by many terrestrial Isopoda, 

 but no one considers that the Isopods mimic the Millipedes or 

 the Millipedes the Isopods. The similarity of habit and form is 

 attributed to homoplasy, and I see no i-eason why the same habit 

 of the cockroaches should not also have been quite independently 

 evolved. 



Having now passed in I'apid review the principal genera, of 

 Blattid;e which show a more or less generalised resemblance to 

 insects of other orders, it only remains to consider in greater 

 detail the genus Prosoplecta Sauss., nearly all the members of 

 which piesent a remarkably close and detailed i-esemblance to 

 <lefinite specific models amongst the Ooleoptei'a, so far as these 

 have been discovered. With but two exceptions the species of 

 Prosoplecta present an appearance which is conveniently sum- 

 marised as Coccinelliform ; that is to say, the outline of the body 

 is ova.l vei'ging on spherical, the form is markedly convex, the 

 integuments are smooth and nitid, the tegmina are corneous 

 with obsolescent venation and do not extend beyond the apex of 

 the abdomen, the legs and antennae are short and, finally, the 

 insects are gaily coloui'ed. It is scarcely necessary to point out 

 that the Coccinelliform type is found amongst other families of 

 Coleoptera besides the Coccinellidse ; it is found, for example, 

 amongst the Cassidida?, Chiysomelidre, and Galerucidfe, whilst 

 many of the Scutellerida?, a family of Hemiptera, also present 

 much the same facies. The two species, P. coccinella Sauss. and 

 P. bipnnctata Br., are, in spite of the name of the fiist, far less 

 Coccinelliform than the other species of the genus, and ma.y 

 certainly be legarded as more primitive. The form is more 

 depressed, and I am inclineil to suppose that these two species. 



