ACHIDIODEA. 203 



are sufficiently definite, assimilates sometimes with 



i/ 



wonderful accuracy with such surrounding's. Ghor- 



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thippus parallelns also varies greatly : the other British 

 members of the Stenobothrus-group do not appear to 

 do so to the same extent, but perhaps this is only 

 because I have met with them in fewer localities, or 

 because the nature of their habitat is less varied. Of 

 our two " club-horned " species, Gomphocerus maculatus 

 varies as much as does Stauroderus bicolor, but G. rufi<* 

 appears to be much more constant. Both the British 

 species of Tetriie are also very variable in their colour 

 and markings. 



For this reason colour .must be but little relied on 

 for distinguishing species. In connection with classi- 

 fication the following are some of the points which are 



most useful, and it is chiefly on these that the accom- 







panying identification table lias been founded : 



1. The foveolae of the vertex little depressions, often 



quadrangular, on each side of the vertex, or top of 

 the head, between the eyes. 



2. The median sulcus (depression) down the centre of the 



frons (containing the median ocellus), the two lateral 

 ones being* less useful. 



3. The colour of the palpi. 



4. The tip of the short antennae, which never consist of 



more than 25 segments. 



5. The position of the cross furrow of the pronotum. 



6. The amount of bending and the position of the angle of 



each of the lateral carinje of the pronotum. 



7. The hind margin of the pronotum, which is usually very 



obtusely angled, but in the genus Tetrix is produced a 

 long way backwards. 



8. The presence or absence of a pad between the claws of 



the tarsi. 



9. The presence or absence of a tooth at the base of the 



valves of the ovipositor. 

 10. The amount of development of the organs of flight in the 



imao-o. 



O 



11. The region of the elytra near the base, between the 



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costa and the sub-costa, that between the sub-costal 

 branches, and in some cases that between the medius 

 and the cubitus. 



