EXTERNAL AN ATOM V OF INSECTS. (381 



which may be regarded as a kind of thumb % are of a 

 lanceolate shape ; in Meloe the external posterior one is 

 flat and obtuse ; in (Enas Latr. it is obconical, concave 

 at the extremity, and apparently furnished with a sucker; 

 in Ateuchus smaragdulus the anterior, and in Copris Ca- 

 rolina the posterior is forked and emarginate; in Sirex the 

 former is hooked and winged ; in Lamprima it is trian- 

 gular and dilated ; in Aphodius analis it is dolabriform ; 

 in Dynastes returns and Juvencus the spurs are bent like 

 a bow. In many Hymenoptcra, as the Sphecida, they are 

 pectinated b , with a series of minute parallel spines — a 

 structure which assists the animal in burrowing ; in 

 Acanthopus Latr. they are armed with little teeth or 

 spines d ; in the hive bee the spur of the cubit is furnished 

 with a membranous appendage which I have called the 

 velum e ; and in a subgenus related to Saropoda Latr. 

 (Ctenoplectra K. MS.), the interior spur of the posterior 

 leg is crescent-shaped, fixed transversely, and fitted on 

 the inner side with a membrane, the edge of which is 

 finally pectinated. 



e. Tarsus or Manus f . This is the last portion of the 

 leg, usually supposed to be analogous to the hand or 

 foot of vertebrate animals ; but, according to the hypo- 

 thesis so often alluded to, rather the representative of 

 their jointed finger or toe. In treating of this part I 

 shall consider its articidation with the tibia, and of its 

 joints inter se ; the number of those joints ; their propor- 

 tion and shape; their parts and appendages. 



a Plate XXVII. Fig. 29. v" . b Ibid. Fig. 33. v '. 



c Linn. Trans, iv. 2.00. Note a. d Plate XXVII. Fig. 32. v" . 



e Ibid. Fig. 36. a: 



f Plates XIV. XV. XXVI. XXVII. a", t". 



