EXTERNAL ANATOMY OF INSECTS.- 601 



portion of an ellipse ; taken separately, it inclines to that 

 of an isosceles triangle, with the exterior side curvilinear: 

 truncated elytra are generally quadrangular, sometimes 

 presenting a trapezium, at others nearly a parallelo- 

 gram, and at others a square. With regard to their 

 proportions they vary considerably, but the most general 

 law seems to be that the length shall exceed twice the 

 width ; in some, as Bnpi-estis Gigas, it is more than 

 thrice ; in many Staphylinidce they are as wide as they 

 are long and sometimes wider ; they are generally nar- 

 rower at the apex than at the base, but in some species 

 of Lycus, as L. fasciatus, &c, the reverse takes place ; in 

 Telephorus they are nearly of the same width every 

 where : with regard to their surface they are sometimes 

 very convex, as in Moluris; at others very flat, as in 

 Eurychora, Aids, &c. 



6. Appendages. These, though not so remarkable as 

 those of the head and prothorax of beetles, ought not 

 to be overlooked. In many Capricorns, as Lamia Tri- 

 bulus, speculifera, &c, the disk and sides are armed with 

 short sharp spines; in others (Stenocorus, &c.) the sutu- 

 ral and anal angles or one of them terminate in a spine 

 or tooth ; sometimes the whole surface, as in Hispa atra, 

 &c, is covered, like a porcupine, with a host of slender 

 spines, or its sides defended by spinose lobes, as in H.eri- 

 nacea .- the humeral prominence is armed with a spine 

 pointing to the head in Macropus longimanus^ and form- 

 ing a right angle with the elytrum in some Cnrcidionid<z, 

 as Rhynchites spinifex,; but the most remarkable ap- 

 pendage of this kind is exhibited by Cassida bidens and 

 its affinities, — from the centre of the sutures of the elytrum 

 rise perpendicularly a pair of long, slender, sharp pro- 



