EXTERNAL ANATOMY OF INSECTS. 663 



regard to the fore-leg, under certain circumstances, as I 

 find them. I shall now consider them in the order in 

 which I have named them. 



a. Coxa or Clavicula a . The coxa is the joint that 

 connects the leg with the trunk of the insect. With re- 

 gard to their shape, the most general form of the four 

 anterior is more or less that of a truncated cone : in the 

 Staphylinidce, however, they tend to a pyramidal or four- 

 sided figure; as do the whole six in the Trichoptera : in 

 numbers of the weevils and capricorns they are subglo- 

 bose; in the Lamellicorns they are mostly oblong, and 

 not prominent : the posterior pair in the Coleoptera are 

 generally flat and placed in a transverse position, and more 

 or less oblong and quadrangular : in Elater, &c, they are 

 cuneiform : in Haliplus Latr. they are dilated, and cover 

 the thigh b : in Buprestis, Copris, &c, they have a cavity 

 that partly receives it : the corresponding part, the cla- 

 vicle, in the arm of Gryllotalpa, is very large and re- 

 markable; viewed underneath it is triangular, and trifid 

 where the trochanter articulates with it : in that of Me- 

 gachile Willughbiella the clavicle is armed with a spine c . 

 As to their proportions, the most general law seems to be, 

 that the anterior pair shall be the shortest and smallest, and 

 the posterior the longest and largest. In some instances, 

 as in Buprestis, the two anterior pair are nearly equal ; 

 in others (Mantis, Eurhinus K.), the anterior are the 

 longest, in the former as long as the thigh, and the four 

 posterior the shortest : in the Trichoptera, Lepidoptera, 

 &c, all are nearly equal ; in Mantis the two posterior, 

 and mPhengodes the intermediate pair are the largest; but 



■ Plates XIV. XV. XXVII. .p. b Plate XV. Fig. ] . p", r" . 



c Plate XXVII. Fig. 27- 



