222 Longicornia Mahyana. 



DORCADIONIN^. 



Only two species of this sub- family occur in the Wallacean 

 Collection, both having a very close resemblance to the European 

 genus Parmcna. No doubt many more forms remain to be dis- 

 covered, as the Asiatic and Australian members of this group are 

 amongst the rarest of insects known, and whilst new species occa- 

 sionally occur, it is rare indeed to see a second example of an 

 older one. They are probably for the most part nocturnal insects 

 like ParmoHi, lurking by day under stones or fallen trees, or in 

 hollow stems of plants, rarely straying far from their hiding-places, 

 in which their race, in some cases,* have probably existed from 

 the time before the earth received its present form. 



One of the peculiarities of this sub-family is the power which 

 many species possess of making a creaking sound when seized or 

 disturbed. This sound^ is produced by the movement of the 

 prothorax on the mesothorax, which, at that part, appears to be 

 perfectly smooth, but under the microscope is seen to be trans- 

 versely striated. It seems to me that these sounds are naturally 

 caused by the attempts of the insect to escape, and that it is not 

 a power given as a means of protection to frighten its enemies. 



The rounded or obsolete shoulders, always connected with the 

 absence of wings, or at most the presence of very rudimentary 

 ones, is the principal feature of this sub-family, which otherwise 

 varies considerably. The typical form appears to be the genus 

 l^/iantasis of M. J. Thomson, leading away on one side to iMicro- 

 trngus, Athevuslvs, Dotcadion, Purmena, Sec, and on the other to 

 Blax and Xylotoles through Deucalion, Dorcadida, Br'imus, and 

 Phrissoma. Hoplonotus, Auxa, Acouodes, and a few others, must 

 stand for the present as more or less isolated forms. 'I'lie 



* Mr. Wollaston (Insecta Maderensia, pp. 430 et seq), in an interestinji; 

 account of the discovery and habits of Deucalion desertarum, says, "Wlieii 

 we consider indeed the apterous nature of Deucalion, its subconnate elytra, 

 and its attachment (at any rate in the larva state) to the interior of the 

 stems of particular local plants, or its retiring propensities within the cre- 

 vices of rocks, wc are at once struck with the conviction that, during the 

 enormous interval of time which has elapsed since the mighty convulsions 

 which rent asunder these regions terminated, it has probably never removed 

 many yards from the weather-beaten ledges which it now inhabits." Another 

 species, which Mr. Wollaston has referred to the same genus {D. oceanicus), 

 was found on one of the Salvages, a mere cone of rock in the midst of the 

 ocean, and must have existed there before the Atlantic islands became 

 detached from the great continental land, of which they once formed part. 



