io8 



HARDWICKE'S SCIENCE-GOSSIP. 



mandible arises within the epicranial vault ; its fibres 

 converge to a chitinous tendon, which passes outside 

 the central plate of the tentorium, and at a lower 

 level through a fold on the lower border of the 



the gena, and is inserted close to the outer side of the 

 condyle of the mandible. 



The anterior maxilla lie behind the mandibles, 

 and like them are unconnected with each other. 



Fig. 59. — Fore-half of head, with tentorium, 

 seen from behind. X 12. 



Fig. 62. — Head of P. orienialis, back view. 

 ca, cardo ; st, stipes ; ga, galea ; la, lacinia ; 

 pa, palp ; stn, submentum ; m, mentum ; 

 PS, paraglossa. X 10. 



{.: -.■-.in 



Fig. 60. — Head of P. orienialis ; front 

 view. X 10. 



Fig. 61. — Head of P. orienialis ; top 

 view, ep, epicranial plate ; oc, eye ; 

 ge, gena. X 10. 



Fig. 63. — Ventral plates of neck and thorax 

 of marie cockroach. I., prosternum ; II., 

 mesosternum ; III., metasternum. X 6. 



clypeus, being finally inserted near the ginglymus. 

 A short fle-xor arises from the crus of the tentorium. 

 The extensor muscle arises from the side of the^head, 

 passes through the fold formed by the lower end of 



They retain much more of the primitive structure of 

 a gnathite than the mandibles, in which parts quite 

 distinct in the maxillcc are condensed or suppressed. 

 The constituent pieces are seen in fig. 62. Of these. 



