694 EXTERNAL ANATOMY OF INSECTS. 



three, as the Tabanidce* ; but also in many of the subse- 

 quent Orders : thus, in the Heteropterous Hemiptera, in 

 Scutcllera and Pentatoma, but not the Reduviadce, and 

 in the Neuropterous genus Nymphes Leach there is a mi- 

 nute one under each claw. It is discoverable between the 

 claws in many Hymenoptera, as Apis b , Vespa, &c. But 

 the genus that exhibits to the curious Entomologist the 

 most singular and elaborate apparatus of this kind is 

 Dytiscus Latr. ; and the examination of the under side of 

 the hand of any male of this genus will almost compel the 

 most inattentive observer to glorify the wisdom and skill 

 of the Allfather so conspicuously manifested in the 

 structure of these complex organs. For this part in these, 

 instead of two or three pedunculate cups as in the in- 

 sects just mentioned, is composed of a vast number, some 

 large and some small. If you take a male specimen of 

 the common D. marginalis, you will find that the three 

 first joints of the hand are very much dilated, so as to 

 form a plate or shield nearly circular, fringed all round 

 with stiffish hairs ; if you next examine the under side of 

 this plate with a good magnifier, you will discover at the 

 base, where it is united to the cubit, two circular cups, 

 the external one more than three times the size of the 

 other, with an umbilicated centre ; besides these two 

 larger cups the rest of the shield is covered by a vast 

 number of minute ones of a similar construction d : the 

 larger cups are nearly sessile, but the smaller are 

 elevated upon a tubular footstalk e ; the three first joints 

 of the intermediate tarsi are also dilated, but not into an 



a Plate XXVII. Fig. 54. Phiios. Tram. 1816. t. xviii./. 9—11. 

 » Plate XXVII. Fig. 55. t. « Plate XV. Fig. 9. a. 



' ,bicI - b - e Phiios. Trans. 1816. t. xx. /. 9, 12-15. 



