DISSECTION. 169 



d. The tibia is a slender straight segment armed with 



strong spines. 



e. Tlie tarsus, or foot, is six-jointed, each segment 



having a soft white setose patch under its distal 

 end, giving the animal a foothold in climbing 

 steep or slippery surfaces. The terminal piece 

 or pulvillus is small and bears a pair of claws. 



3. Abdominal appendages are very rare amongst adult in- 

 sects. The anal cerci already described, and possibly 

 also the styles on the ninth sternum of the male, may 

 be appendages, as also may the gonapophyses ; but 

 it is doubtful whether these really belong to the 

 same category as the appendages of the head and 

 thorax. 



The gonapophyses belong to the genital appa- 

 ratus, and will be described later. 



111. DISSECTION OF THE COCKROACH. 



Fix the animal down with the dorsal surface ujnvards. 

 This may be done by drying it loith blotting paper, and 

 immersing its under surface in melted paraffin or loax, and 

 holding it in this position till the wax is cool : or the animal 

 may be fixed to a board by means of small pins passed through 

 the lateral regions of the mesothorax and of the abdomen. 



Fig. 38. — Periplaneta Americana. The male dissected from the right 

 side. The testes and vasa deferentia are not figured, (o. h. h.) 



A, anus. AiN", antennary lobe of supra-oesopbageal ganglion, with anten- 

 nary nerve cut short. C, crop. CG, supra-cesophageal ganglion. CL, colon. 

 CR, anal cercus. CX. coxa. E, elytron. F, femur. FGr, frontal ganglion. 

 F3S", visceral nerve. G-, gizzard. G-P, one of the gonapophyses. Gr 5, iifth 

 abdominal ganglion. H, hepatic cfficum. HT, heart. I, ileum. L, lingua. 

 LiN", nerve to labrum. LP, labial palp. M, mushroom-shaped gland. 

 MC, Malpighian cffica opening into junction of mesenteron and ileum : they 

 are much longer and more numerous than indicated. MD, ejaculatory duct. 

 ME, mesenteron. MW, maxillary nerve. MP, maxillary palp. PJS", labial 

 nerve. PP, podical plate, diagrammatically drawn. R, rectum. S, sub-ceso- 

 phageal ganglion. S!D, salivary duct just above its opening into the mouth. 

 SG-, salivary glands. SL, style borne by ninth sternum. SR, salivary 

 receptacle. ST, one of the abdominal stigmata. T, proximal joint of the 

 tarsus. TB, tibia. TR, trochanter. T 1, first thoracic tergum, or pronotum. 

 T 3, third thoracic tergum, or metanotum. VG, visceral ganghon. "W", wing. 

 2, tergum of second abdominal segment. 8, tergum of eightli abdominal 

 segment. 10, teigum of tenth abdomical segment. 



