80 



THE COCKROACH 



where the eight hard chitinous plates or sclerites occur, there being two dorsal, 

 two ventral, and two lateral pairs of these plates. 



The antenna are attached to the front of the head immediately below the 

 eyes. Each antenna consists of a stout basal joint, movably articulated, by a 

 ring of soft cuticle, in a cavity of the clypeus. On the inner and upper side of 

 each antenna is a small circular white area, situated at the end of the suture 

 dividing the epicranium from the clypeus. These areas are called the fenestrse. 



Make three drawings of the head to show (i) the front, (ii) the side, and (iii) 

 the dorsal aspect. 



Tarsus 



MANDIBLE 



Subraentum 



Labial palp 



Lacjnla 



MaxillaiV 

 palp 



Stipes 



LEFT METATHORACIC LEQ 



SECOND MAXILL/E 

 (LABIUM) 



FIRST MAXILLA 

 (OF LEFT SIDE) 



Fig. 26. — Appendages of the Cockroach {Periplaneta americana). The part of the second maxilla 

 marked L is the glossa, which corresponds to the lacinia of the first maxilla. 



The Mouth Parts. 



Remove the labrum so as to expose the mandibles. Each mandible is 

 attached by a convex condyle to the lower end of the epicranial plate, and also by 

 a concave anterior articulation to the clypeus. Remove and draw a mandible, 

 noting the strong tooth-hke process of chitin. 



Situated just behind the mandible of either side is the 1st maxilla. Remove 

 and draw the 1st maxilla, noting its parts : — A basal two- jointed portion con- 

 sisting of the cardo and the stipes. The cardo is a transverse plate bent upon 

 itself and bearing the stipes. To the side and lower end of the stipes is attached 

 the five-jointed maxillary palp, while the lacinia and galea are articulated to its 

 extremity. The lacinia is internal and posterior to the galea. Its base is 

 broad and it narrows to a bifid tooth of hard chitin. Its inner surface is beset 

 with a cluster of strong setse. 



On the posterior Surface of the head, below the occipital foramen, the lower 

 lip or labium is situated. It is formed by the fusion of the basal portions of the 



