THE MYRMECOPHILOtJS COLEOPTEKA 335 



Dinarda hagensi and pygmcea have undoubtedly been evolved much more 

 recently and have not perhaps become quite fixed, as they vary somewhat in 

 tliemselves. 



It may be as well to reproduce here part of my translation of Wasmann's 

 paper on the " Evolution of Dinarda,'' which appeared in the Zoologist for 

 February 1908 : 



" As an instance of recent species building I brought forward in 1901 the 

 genus Dinarda, in the Brachyelytra (Staphylinidce). It can be shown that 

 our North and Central European two-coloured (red and black) forms of 

 Dinarda, which are adapted to different species or races of the genus Formica, 

 stand in different stages of species building. Two of these — Dinarda dentata 

 (with F. sanguinea) and D. markeli (with F. rufa) — have already become 

 throughout their area of distribution such constant forms that they have 

 been hitherto not incorrectly treated as species. Two other nearly related 

 forms, on the other hand — D. hagensi (with F. exsecta) and D. pygmma (with 

 F. rufiharhis, and especially with the var. fusco-rufiharhis) — are still considered 

 to be in the process of adaptation to their ant-hosts ; in some parts of the area 

 of distribution of the latter they have already become well-defined forms : 

 in other regions they still show numerous transitions towards D. dentata ; 

 finally in others, no adaptation of Dinarda to F. exsecta and rufiharhis has 

 yet taken place. We have also before us in these two forms of Dinarda, 

 ■s^'hich gradually approach in the path of variety and race-building, every 

 stage of species building which has already been reached by Dinarda dentata 

 and markeli. . . . The sooner the adaptation of Dinarda to F. exsecta and 

 rufiharhis has taken place in a region, the more they are protected, through 

 local isolation of the ants' nests in question from those of allied species of 

 Formica (especially of F. sanguinea), and so much the further has also the dif- 

 ferentiation of the forms of Dinarda in question progressed. This is most 

 clearly shown as yet in the differentiation of D. pygmcea from its ancestral form 

 dentata. Also as regards D. hagensi, some new facts have been added in 

 the last two years, Avhich show that its adaptation to F. exsecta is not yet 

 completed, but that in different points of its area of distribution it stands 

 at different stages in the process of species building. Donisthorpe found a 

 number of Dinarda with F. exsecta at Bournemouth, which come nearer to 

 the typical examples taken by Von Hagens in the Siebengebirge in 1855 than 

 the Dinardas taken by me at Linz on the Hhine with the same ant in 1893- 

 1901. Most of these English examples show, just as Von Hagens's type, 

 no raised keeled border to the elytra, but these organs are regularly arched, 

 in which these examples even depart from the generic diagnosis of Dinarda 

 ('elytrorum margine laterali carinato '). Also the antennse are shorter 

 and more compact than in D. dentata. On the other hand, the border of the 

 elytra in the examples from Linz is distinctly raised and keeled, and the 

 antennae are somewhat more slender than in dentata. In some of Donis- 

 thorpe' s examples from England transitions between both the hagensi forms 

 are noticeable in that the border of the elytra is sometimes feebly raised, and 

 the antennse are less compact. Dinarda hagensi has evolved, at different points 

 of its area of distribution, so far as to reach different stages towards a peculiar 



