688 EXTERNAL ANATOMY OF INSECTS. 



extremely short as to be scarcely distinguishable from 

 each other : it is the shortest of all in Colymbetes, &c. ; 

 it is of the length of the third in Cicindela sylvatica, of 

 the fourth in C. sexguttata. Though commonly the slen- 

 derest joint of all, particularly so in Raphidia, in many 

 Heteromerous and Lamellicorn beetles it is the largest, 

 conspicuously so in Mellinus tricinctus. Sometimes, as 

 in Buprestis chrysfc, &c, all the tarsal joints are nearly 

 equal in length and thickness. 



•We are next to say something upon the shape of the 

 tarsi and their joints. In general we may first observe 

 that their upper surface is commonly more or less con- 

 vex, and the lower flat or concave : in insects that are 

 swift runners, as the terrestrial Predaceous beetles, they 

 are usually slender and filiform a ; in those that swim, as 

 Dytiscus, the two posterior pair taper nearly to a point 

 from the base to the apex b ; in some that climb, as Bu- 

 prestis, they are rather flat and linear ; and in others (the 

 Weevils, Curculio L.) they grow gradually wider towards 

 the claw-joint e ; sometimes, as in Mordella Latr., the four 

 anterior tarsi are of this shape, and the posterior pair 

 setaceous. In Gyrinus the four posterior are flat and 

 triangular ; and in that extraordinary insect Gryllus mon- 

 strosus the tarsi are foliaceous and lobed d . In many 

 males and some others the anterior pair or hands are of 

 a different shape from the two posterior : thus, in several 

 Carabi they are lanceolate; in Staphylinus, Creophilus, 

 &c. in both sexes they are often nearly circular, like 

 those of male Dytisci e . With regard to the shape of 



a Plate XIV. Fig. 7- 1". •> Ibid. Fig. 6. t". 



4 Plate XXVI. Fig. 47. * Plate XXVII. Fig. 41 . 



e Plate XV. Fig. 9. 



