502 ME. W. r. KIRBT OK FORFTCULID^. 



ditary diseases, means that there is at present in the subject a 

 minor condition of the nature of a congenital malformation. It 

 is possible that under the most favourable conditions of life for 

 the given defect it may never lead to a breakdown or become 

 apparent, whilst under other and less favourable circumstances 

 the weak point may give way and the defect become obvious. 

 Such an explanation as this might be without hesitation accepted 

 as accounting for the varieties of eye-defects recently referred to ; 

 and I believe that further investigation will show, as far as 

 demonstration is possible, that the same line of argument may 

 be used, not only with regard to the remaining diseases of the 

 hereditary group described as (3) in Section V., but also to some 

 at least of the congenital and hereditary malformations as well. 



A Eevision of the Forficulidce, with Descriptions of New Species 

 in the British Museum. By W. F. Kiebt, F.L.S., E.E.S., 

 of the British Museum (Natural History). 

 [Eead 19th June, 1890.] 

 (Plate XII.) 

 The Forficulidse, or Earwigs, have hitherto attracted less atten- 

 tion from Entomologists than any other group of Orthoptera. 

 There are but few papers of any importance on the group ; those 

 by Dohrninthe ' Stettiner entomologische Zeitung' (vols. 24-26, 

 1863-1865), which include a descriptive synopsis, and Scudder's 

 Catalogue of all the described species, in vol. 18 of the 'Proceedings 

 of the Boston Society of Natural History ' (1877), being the most 

 useful. Siijce then several species have been described by De 

 Bormans, Karsch, and others in various foreign periodicals. 



Having lately rearranged this group in the British Museum, I 

 judged that it would give a useful impetus to its study to publish 

 a revised synopsis of the genera on the lines already indicated by 

 Dohrn and De Bormans, and to describe as many new species as 

 were before me in sufficiently good condition. Several of these 

 were ticketed with MS. names by Prof. "Westwood, which I have 

 usually adopted. 



One great drawback in the study of the Eorficulidse is deficiency 

 of material. They are usually received in very small numbers 

 and rarely in quite perfect condition, the antennae, which are 



