86 THE ENTOMOLOGIST. 



19. P. (Adelosia) pkimanus, Duftschm. — Fully winged. 

 Wings, 10 mm. by 4 mm. ; elytra, 7i mm. long. Two specimens 

 examined (Slieppey, Commander Walker). 



20. P. (Pediiis) incequalis, Marsh. — Flightless. Vestigial 

 wings minute, scarcely h mm. long ; elytra almost 4 mm. long. 

 One specimen (Southend, February 14th, 1863). 



21. P. {Lagariis) vernalis, Gyll. — Fully winged. Wings, 

 4-5^ mm. long, \h-'^\ mm. wide : elytra, 4 mm. long. 



This is an interesting form, the wings being rather small in 

 proportion to the elytra, and subject to considerable diminution, 

 which, however, occurs rather on the axillary part of the wing, 

 not on the apical part. 



I have examined sixteen specimens. Seven from Paignton 

 (Perkins, November 5th, 1909), five of which have the wings 

 conspicuously less than full size, while the other two have very 

 nearly the full length of wing, but with the axillary portion 

 small in size. Five individuals from Wicken (Donisthorpe, 

 April 22nd, 1910) have the wings of full size (slightly over or 

 slightly under 5 mm.). One example (Oxford, November, 1909, 

 Walker) has the wings quite of full amplitude. Two from Boar's 

 Hill, Oxford (Donisthorpe, April, 1909) differ distinctly, one 

 having the wings nearly of full size, while in the other they are 

 markedly reduced, being a little less than A^ mm. long. One 

 specimen from the New Forest (May 1st, 1912) has the wings 

 very nearly of full amplitude. 



The variation in this species would appear to be peculiar, as 

 though the wings exhibit frequently considerable reduction in 

 amplitude, there is no production of a second form of wing such 

 as exists in P. minor. The variation, too, appears to be more 

 affected by locality than it is in other species. But it must be 

 admitted that the number of specimens examined is not enough 

 on which to base any important conclusions. 



22. P. {Ahax) sfriok.— Flightless. The vestigial wings re- 

 duced to small rudiments about \ mm. long. The metanotum 

 very short, the elytra soldered. The nearest of all our Ptero- 

 stichus to a really apterous state. 



The number of species is twenty-two ; ten of them are 

 flightless, eleven are fully winged, while one is dimorphic, having 

 about half its individuals in one or other of the two conditions. 



The wings are always present, though in some species the 

 vestiges are quite minute. The vestigial wings, though quite 

 different in shape from the normal wings, exhibit shapes charac- 

 teristic according to the species. Both normal wings and ves- 

 tigial wings are apt to exhibit considerable variation — the varia- 

 tion is perhaps greater in the case of the vestiges ; this is a point 

 difficult of determination. 



Variation does not appear to be connected with sex, and only 



