EXTERNAL ANATOMY OF INSECTS. 539 
inwards, lap at the end one over the other, so as to form 
a circular orifice for the head, which otherwise would be 
quite covered by the shield. Thus the upper portion of 
the eyes can see objects above, as well as their lower por- 
tion those below. I might enumerate many other forms, 
but these are sufficient to give you some notion of the 
variations of this part. 
5. The prothoraz is equally various in its sculpture ; 
but since in the Orismological table almost every instance 
of it has its place, I shall here only notice it as far as it 
is common to the whole tribes, genera, or subgenera. 
The Scarabeide are distinguished by a small excavation 
on each side of this part, which, as has been before re- 
marked *, furnishes an elevated base for an internal pro- 
cess with which the anterior core ginglymate. In Onitis 
and Phancus, to these excavations are superadded a_ 
pair impressed in the base of the prothoraz, just above 
the scutellum ; in Carabus, &c. a longitudinal channel 
divides the thoracic shield into two equal portions; and 
many genera of the great tribe to which it belongs have 
in addition, at the base on each side, one or two exca- 
vations or short furrows. lophorus has on this part 
several longitudinal channels, alternately straight and 
undulated. Generally speaking, in the tribe just alluded 
to, the prothoraz has no impressed points ; but in Chlenia 
and some other genera belonging to it, it is thickly co- 
vered with them. In numbers of Locusta, the part we are 
considering is what Linné terms cruciate, being divided 
into four longitudinal portions by three elevated lines, 
the intermediate one being straight, and the lateral ones 
diverging from it both at their base and apex, so as to 
* See above, p. 397. 
