EXTERNAL CHARACTERS. 



171 



e. The eyes are large black reniform elevations, one 



on each side of the head. They are compound, 

 each having very numerous hexagonal facets. 



f. The fenestra are a pair of small white oval patches 



to the inner sides of the bases of the antennae. 



2. The neck is short and slender : its cuticular covering 

 is soft and white, with the exception of seven 

 thickened patches or sclerites, which are hard and 

 brown. Of these sclerites two are slender trans- 



Eig. 38. Periplaneta americana. The head, front view. (c. h. h.) 

 A, autenna. CL, clypeus. E, eye. EP, epicranium. F, fenestra. G, 

 galea. GE,gena. |_, lacinia. LP, labial palp. LP., labrum. MN, mandible 

 (the left mandible has been removed). MP, maxillary palp. M 2, second 

 maxilla. 



Fig. 39. Periplaneta americana. The head from behind, (c. h. h.) 

 E, EP, G, L, LP, MN, and MP, as in the preceding figure. 

 C, car do. LG,ligula. M, mentum. N, nerve-connective. O, oesophagus. 



PG, paraglossa. S, stipes. SD, salivary ducts. SM, submentum. TR, 



cervical tracheae. 



verse bars on the ventral surface ; a third is median 

 and dorsal, and almost divided into two longitudi- 

 nally ; the remaining four are much larger, and 

 form two pairs at the sides of the neck. 



3. The thorax consists of three segments. 



a. The prothorax is the first and longest segment of 



