1890.1 167 



SYNOPSIS OF THE BRITISH ORTEOPTERA. 



BY ELAND SHAW, F.E.S. 



{^Continued from page 97). 



v.— GRYLLID.^. 



Of the crickets we have five British representatives belonging to 

 four genera. About one of these {(Ecanthus pellucens, Scop.) there 

 must be considerable doubt, for we depend on but one record of its 

 occurrence, and this Stephens, writing in 1835, tells us, took place 

 " many years since." However, it is said to have been taken here 

 once, and let us hope that it may be taken here again, meanwhile re- 

 taining its name in our fauna list until such time as the abundance of 

 negative evidence compels us to erase it. 



The following details of structure should be noticed in the 



British species : — 



The vertex is broad and rounded, and not separated from the frons by a furrow 

 as in the Locustida. (In our European genus Platyhlemmus the vertex is sometimes 

 produced into a lamelliform , process). The position of the ocelli is of importance, 

 and gives some good characters. The antennse are long and filiform. The prono- 

 tum, except in Gryllotalpa, shows nothing of importance. The elytra have a peculiar 

 structure and consist of two portions — an anterior (lateral in a state of rest) and a 

 posterior (dorsal) portion ; and these two are placed almost at a right angle to one 

 another. The homologies of the veins are somewhat difficult to make out, but 

 Saussure has given an excellent nomenclature for them, particularly as regards the 

 modifications of the vena plicata, wliich form the stridulating apparatus, and this is 

 recapitulated and further observations made by Brunner. The mediastinal vein is 

 wanting. There is but one radial vein, and this sends several branches towards the 

 anterior border of the elytron, and is unbranched posteriorly. The ulnar veins are 

 two (anterior and posterior) as in the Acridiida, and run close together, the anterior 

 being much stronger than the posterior, and forming the ridge between the vertical 

 and horizontal (lateral and dorsal) portions of the elytron. The vena dividens runs 

 as usual straight from the base, and is usually somewhat deeply seated. So far the 

 elytra of both sexes are alike ; but in the (? the branches of the vena plicata are 

 modified into a stridulating organ, while in the $ they are simple. In the <J the 

 vena plicata, after a straight course for the first quarter, turns at nearly a right angle 

 towards the posterior margin, and on the under-side is here cross-ribbtd, and is the 

 sound-producing mechanism. Close to the posterior margin the vein turns again 

 sharply towards the anterior margin, the point where it turns is dilated, and is the 

 " noeud anal " of Saussure, from which several branches emerge and spread out like 

 a fan ; the main vein proceeds outwards and forwards till it reaches the last 

 quarter of the length of the elytron, where it joins the vena dividens, and here 

 another dilatation is seen, the " stigma " of Saussure. Thus a triangular area 



