362 MR. ROBERT SHELFORD ON 



Westwood's handwriting attached to it : — "This Blatta lives on 

 trees and closely resembles in its habits some of the large Lam- 

 pyridae [T. Belt]." This is doubtless one of the species mentioned 

 by Belt in his book, and I had great hopes of being able to match 

 it with a definite species of Lampyrid beetle, but the most diligent 

 search through the Godman-Salvin collections of Central American 

 insects failed to reveal a " model " to the cockroach. The Malaco- 

 dermatous appearance is undoubtedly but generalised, not specific. 

 The same may be said of Hypnorna amoena Sauss. & Z., also from 

 Central America. This Blattid has all the appearance of a small 

 Longicorn, but it actually resembles no particular species of that 

 family. It may, of course, be argued that further collecting will 

 bring to light speciesof beetles which can legitimately be regarded 

 as models to the cockroaches, but I do not think that this is in 

 the least degree probable. Our knowledge of the Central American 

 ( Joleoptera must now be nearly complete, speaking from the point 

 of view of the systematist, and the West African Eustegasta 1 n- 

 prestoides is so very abundant that it might reasonably be expected 

 that its Supposed model would be, if not abundant, at any rate in 

 sufficient numbers to permit of some specimens falling into the 

 hands of collectors. At the very end of this paper I describe 

 two new species of Blattidae, belonging to anew genus, which 

 also must fall into the category of generalised Coleopterous 

 mimics. 



The two species of the Oriental genus Tkyrsocera Burm. are 

 shining black cockroaches with large yellow spots on the tegmina, 

 a type of coloration frequently met with amongst the Endomy- 

 chiihe of the same region. These cockroaches, though far larger 

 than, and in other points quite unlike any Endomychidse known 

 to science, may possibly be regarded as part of a "convergent 

 group," the dominant or "central" members of which are the 

 yellow-spotted Endomychidae (genus Eumorphus). A generalised 

 resemblance to certain families of Rhynchota is also shown by 

 some Blattidse. For example, some species of Holocompsa Burm. 

 and Hypercompsa fieberi Br. are rather like small Capsidae; the 

 illusory effect is produced by the tegmina, which are largely 

 membranous and hyaline, though opaque and coriaceous at the 

 base; the resemblance does not bear a very close examination. 

 Homopteroidea nigra Shelf, is not unlike some small Fulgorid or 

 Jassid. Mr. J. C. Kershaw found at Hong-Kong, under a stone, 

 several little black Pentatomids, and in company with these a 

 similarly coloured and shaped cockroach which appears to be 

 identical with Psevdophyllodromia parilis Walk., and he sug 

 gested* that the cockroach mimics the bug. Having seen the 

 specimens I prefer to regard them as examples of syncryptism or 

 of homoplasy. 



Linnaeus, deceived by the Coleopterous appearance of Corydia 

 petiverana, placed it in his genus Cassida. Mr. T. Bainbrigge 



* In a letter In Professor Poulton. 

 [6] 



