BRITISH AND FINNISH SPECIES OF ACRYDIUM. 243 



a, Posterior extension of prothorax extending consider- 

 ably beyond apex of femora. Wings a little longer 

 than prothorax Forma macroptera [ = A. subiilatiis (Auct.)) 



ft. Posterior extension not or scarcely extending beyond 

 apex of femora. Wings little explicate, a little shorter 

 than prothorax. 



Forma brachyptera ( = subsp. A. sahlbergi (Saulcy) ) 



4. 1. Dorsum of prothorax distinctly tectiform, median keel 



considerably elevated, and anteriorly (seen in profile) 

 roundly-declivous. Head apically somewhat obtuse, 

 frontal line roundly continued on the vertex. Species 

 generally short-winged. 



5. 6. Antennae slender, fourth and fifth segments equal in 



breadth, four times as long as the middle segments, 

 three times as long as penultimate and middle keel of 

 vertex, in the middle of the apex, reaching a little 

 beyond the lateral keels. Anterior margin of pronotum 

 fairly straight. Posterior metatarsus with obliquely 

 angulate pulvilli. Dorsal spots transversely sublunate- 

 triangular . . . . .A. tenuicornis (J. Sahib.) 



6. 5. Antennae somewhat incrassate, fourth and fifth segments 



strongly, sixth distinctly transverse, penultimate twice 

 longer than wide. Head as in tenuicornis. Pronotum 

 with anterior margin distinctly angulate. Posterior 

 metatarsus with insignificant pulvilli, beneath straight. 

 Dorsal spots generally distinctly rhomboidal, auteri- 

 orily obliquely placed . . . .A. bipunctatus (L.) 



a. Prothoracic exteusion extending far beyond apex of 

 femora. Wings explicate, distinctly longer than pro- 

 thorax. Forma macroptera. 



ft. Prothoracic extension reaching apex of posterior femora. 

 Wings not explicate, much shorter than prothoracic 

 process . . Forma brachyptera [A. bipunctatus (Anct.)) 



It will be seen from the above that the characters relied upon 

 by British workers for the specific differentiation of subulatus and 

 bipunctatus refer apparently only to the brachypterous form of 

 the former, and to the macropterous form of the latter. It is 

 to be hoped that this genus will be actively searched for and 

 examined, as it is quite possible that all the forms described 

 above may occur with us. 



I have followed Kirby in the use of the name Acrydium 

 (Geoffr. 1762), which has undoubted right of priority over 

 Tetrix, Latr. 1802 (usually written — as, indeed, by Sahlberg, 

 Burr, and Lucas — Tettix), 



