LOCUST 175 



proportion of the head does it cover ? What 

 is its color? Note the central ridge with a 

 simple eye or ocellus in the middle line. 



Fastened to the lower edge of the epicra- 

 nium is 



(b) The clypeus. — How does it compare in size 

 with the latter? Does it consist of a single 

 piece ? Does it bear any ridges ? 



(c) The gense or "cheeks." — Which of the 

 above structures do they touch at their edges ? 

 What is their shape ? 



Below the clypeus is 



{d) The labrtim or "upper lip." — Kaise it up 

 with the point of a pin. To what is it attached ? 

 What is its shape ? What range of motion has 

 it ? Draw. 

 . Mouth parts. 



As was done with lobster or crayfish, remove 

 and study also the following 



{a) The labrum (already examined). 



(5) The labium or " under lip." — Compare in 

 every respect with the labrum. Does it look 

 as though it were made of two parts which had 

 fused together along the middle line ? Try to 

 make out the following parts : the submen- 

 tujn, composed of two protopodites fused to- 

 gether, the hinder curved portion forming the 

 gula ; the mentum, which is the fused distal 

 joints of the protopodites and bears the endo- 

 podites, which together form the ligula ; the 

 palpi supported on a stump-like base or palpi- 

 ger and representing the exopodites. 



(o) The labial palpi. — How many? Where and 

 how are they attached to the labium? Are 



