DISSECTION. 177 



d. The tibia is a slender straight segment armed with 

 strong spines. 



e. The 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. 



III. DISSECTION OF THE COCKROACH. 



Fix the animal down with the dorsal surface upwards. 

 This may be done by drying it with blotting paper, and im- 

 mersing its under surface in melted paraffin or wax, 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. 40. Periplaneta americana. The male dissected from the right 

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



A, anus. AN, antennary lobe of supra-oesophageal ganglion, with anten- 

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

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

 FN, visceral nerve. G, gizzard. GP, one of the gonapophyses. G 5, fifth 

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

 LN, nerve to labrum. LP, labial palp. M, mushroom-shaped gland. MC, 

 Malpighian caeca opening into junction of mesenteron and ileum : they are much 

 longer and more numerous than indicated. MD, ejaculatory duct. ME, 

 mesenteron. M N , maxillary nerve. MP, maxillary palp. PN, labial nerve. 

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

 ganglion. SD, 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 ganglion. W, wing. 2, tergum 

 of second abdominal segment. 8, tergum of eighth abdominal segment. 10, 

 tergum of tenth abdominal segment. 



