4 Mr. Gilbert J. Arrow's Contribution to the 



Genus Trycherus. 



Since Gerstaecker's excellent monograph of the Endo- 

 mychidae, in which hve species of Trycherus were described, 

 the various additions made have been so inadequately 

 characterised as to introduce ever-increasing confusion 

 which nothing but the comparison of the types can now 

 resolve. The British Museum happily possesses most of 

 these by its acquisition of Mr. Gorham's Endomychidae 

 and those of the great Ery bequest, the former containing 

 tvpes of four of the five species of Gerstaecker and a co-type 

 oil. longanirnis Thoms. I have therefore been in the 

 fortunate position of having under my eyes the types of all 

 the species of the genus hitherto described, except T. 

 hifascialus Gerst., rajfmyi Gorh., josephus Duv., elegans 

 Cziki, and redicollis Har. The last species I do not Imow ; 

 elegans Cziki, as already noted by Fairmaire, appears to 

 agree in all respects with longanimis Thorns., a,nd the other 

 three species I have determined from the descriptions. 



There is an excessive external similarity betAveen many of 

 the species of the genus, and the most important distinctive 

 features are the secondary sexual characters. The im- 

 portance of these was emphasised by Gerstaecker, but all 

 subsequent describers liave persistently neglected them. 



The distribution of the genus is very interesting. The 

 Catalogue of Cziki, published in 1910, enumerates thirteen 

 species (excluding an Oriental form which certainly belongs 

 elsewhere), all but one {T. raffmyi) described from W. Africa. 

 That species also occurs in Angola, as shown by a specimen 

 in the British Museum. One other species (T. fryanus) 

 occurs in E. Africa (Rhodesia and Zanzibar), and it is 

 remarkable that that also was described from Angola. 

 Since the alhed genera are those of Madagascar and the 

 Malayan region t'liis marked preference for the western side 

 of Africa is striking. Of the thirteen species four have been 

 recently received from Uganda, and no less than seven 

 others are here described from the same region . These may 

 be expected to occur also in W. Africa. Thus, although 

 the species existing are evidently numerous and by no 

 means narrowly localised, the genus seems to have no truly 

 E. African species. The eastern specimens of T. fryanus 

 and T. raffra.yi must be supposed to have straggled there in 

 comparativeiv recent times. It is certainly curious that m 

 spite of a bold effort to extend eastward, resulting in their 



