410 EXTERNAL ANATOMY OF INSECTS. 



bears the propedes, consequently on the mesothorax ; and its 

 four divisions will then be the prtsscidum, scutum, scutellum, 

 and I) ost scutellum of the mesothorax, according to Andouins 

 nomenclature ; the metathorax will probably be concealed, as 

 in the Musca; ; and the nine posterior segments are found of uni- 

 form development, as in the Tipula;. These conclusions would 

 place Stylojjs very near the Diptera, a locality which a cer- 

 tain similarity of its head to that of Myopa, Conops, &c. 

 would rather favour. So much from figures ; as the greatest 

 accuracy and care is requii'ed to avoid the destruction of such 

 minute creatures in dissecting, errors may possibly have crept 

 in ; my motive for inti'oducing a passing notice of Sty lops in this 

 place is, that should the part in question prove to be the 

 metathorax, as has been hinted, then its natural station is the 

 one which MacLeay has assigned it between Hymenoptera 

 and Coleoptera; and, consequently, in passing from one of 

 the classes to the other, it becomes compulsory to mention it. 

 In Coleoptera the metathorax has reached a still greater de- 

 velopment, and is nearly of equal dimensions with the protho- 

 rax ; it is however entirely hidden under the proalce when 

 these are closed. In Orthoptera, particularly in some 

 PhasmcR, the metathorax has reached its maximum. In 

 Hemiptera it has much decreased, although still the principal 

 organs of flight arise from it ; at least this is the case in the 

 Chnicites ; but in the Cicadites the proalce, have resumed 

 the full functions of flight ; and, as I have already observed, 

 the mesothorax is enlarged at the expense of the pro- and 

 metathorax. The articulation of the mesothorax and meta- 

 thorax is fixed. 



The fifth segment is the Propodeon, and is, of the whole 

 thirteen, the most difficult to determine, because in orders of 

 the same class it appears in different modes : in Lepidoptera, 

 generally, I believe its external appearance is that of a narrow 

 ring slightly incrassated in the middle, and assuming, when 

 viewed from above, a somewhat bow-shaped figure. In Cossus 

 it appears to me to be the part which Kirby calls the meta- 

 thorax,^ which I think it cannot be ; as the metalce are 

 decidedly not attached to it. In Pterophorus it is very 

 distinct, and varies scarcely at all from the following segment ; 



' Int. to Ent. PI. IX. Fig. 1. 



