536 EXTERNAL ANATOMY OF INSECTS. 
is armed by a most singular and wonderful apparatus of 
balls and spines,—in one case standing erect*, and in 
the other being horizontal >,—-which gives these animals 
a most extraordinary appearance. In many of the species 
here quoted the prothoraz is producted posteriorly into 
a long scutelliform horizontal horn, which more or less 
covers the wings and abdomen; a circumstance which 
also distinguishes the genus Acrydium. This horn seems 
to have been sometimes regarded by Linné and Fabri- 
cius as areal scutellum, and sometimes only as a process 
of the prothorax: but that it is merely the latter will be 
evident to you, if you examine carefully any insect fur- 
nished with this appendage ; for if you remove that part, 
you will discover the true scutellum and other parts of 
the trunk concealed beneath it. A very remarkable pro- 
thoracic appendage is exhibited by some species of 
Mantis. In general the part we are treating of in this 
tribe is very slender; but in M. strumaria, gongylozdes, 
&c. it appears dilated to a vast width, and assumes, either 
partially or generally, a suabrhomboidal form ; but ifit is 
more closely examined, it will be found that the form of 
the prothoraz is really similar to that of the rest of the 
tribe, but that this part is furnished on each side, either 
on its whole length or anteriorly, with a large, membra- 
nous, flat, subtriangular appendage resembling parch- 
ment‘. Perhaps this kind of sail may be useful to the 
animal in flight. Im Prionus, coriarius, &c. its sides 
are armed with teeth, and in many Lamia, Cerambyces, 
and other Capricorn beetles, and often in various bugs 
* Stoll Cigales t. xxviii. f. 163. 
» [bid. t. xxi. f. 115. Coquebert Jilust. Te. ii. t. xviii. f. 5, 
* Stoll Spectres t. xi. f. 42. t. xii. f. 45, ¢. xvi. f. 58, 59, 
