346 MISS E. J. BECK ON THE MUSCULAR 
the arthrodio-sternal obliquus muscle (33) of the fifth segment of the mesosoma, and 
the arthrodio-sternal obliquus muscle (34) of the sixth segment of the mesosoma are 
similar in form and position to the arthrodio-sternal obliquus muscle (31) of the third 
segment of the mesosoma. 
The post-stigmatic muscle (35) of the third segment of the mesosoma is a small 
muscle attached anteriorly to the posterior edge of the stigmata of the lung-sac, and 
posteriorly to the arthrodial membrane posterior to the segment (for the post-stigmatic 
muscles see Pl. LX XVIII. figs. 8 & 9). 
The post-stigmatic muscle (36) of the fourth segment of the mesosoma, the post- 
stigmatic muscle (37) of the fifth segment of the mesosoma, and the post-stigmatic 
muscle (38) of the sixth segment of the mesosoma are similar muscles to the post- 
stigmatic muscle (35) of the third segment of the mesosoma. 
c. Metasoma. 
Dorsal.—The arthrodio-tergal rectus muscle (39) of the first segment of the meta- 
soma is a small muscle attached posteriorly to the arthrodial membrane posterior to 
the segment; running forwards by the side of the pericardium it is attached anteriorly 
to the tergite. 
The arthrodio-tergal rectus muscle (40) of the second segment of the metasoma is 
attached posteriorly to the arthrodial membrane posterior to the segment; running 
forwards by the side of the median line it spreads out anteriorly, and is attached to 
the tergite. 
The arthrodio-tergal rectus muscle (41) of the third segment of the metasoma and 
the arthrodio-tergal rectus muscle (42) of the fourth segment of the metasoma are 
exactly similar to the arthrodio-tergal muscle (40) of the second segment of the 
metasoma, 
The arthrodio-tergal rectus muscle (43) of the fifth segment of the metasoma is a 
narrow muscle attached posteriorly to the arthrodial membrane posterior to the segment 
which runs forward by the median line, and is attached to the tergite. 
The arthrodio-tergal rectus muscle (44) of the sixth segment of the metasoma is 
narrow and long: it is attached to the arthrodial membrane posterior to the segment, 
and runs forward by the median line, being attached anteriorly to the tergite. 
The arthrodio-tergal obliquus muscle (45) of the first segment of the metasoma is a 
small muscle attached posteriorly to the arthrodial membrane posterior to the segment. 
It runs obliquely forward, towards the median line, and is attached anteriorly to the 
tergite. This muscle is similar to the arthrodio tergal obliquus muscles (9-14) in the 
segments of the mesosoma. 
The arthrodio-tergal obliquus muscle (46) of the second segment of the metasoma, 
the arthrodio-tergal obliquus muscle (47) of the third segment of the metasoma, and 
the arthrodio-tergal obliquus muscle (48) of the fourth segment of the metasoma are 
