HANSEN, II. J.: IIEMIMERUS TALPOIDES WLK. 77 



first pair, can be discovered with certainty witliout special pre- 

 paration. In order to examine their number and position I opened 

 longitudinally the back of a female with a pair of scissors, put 

 it into a strong, cold dissolution of caustic potash during 24 

 hours and then into glycerine. The more general features of the 

 tracheal system are now rather easily studied with transmitted 

 light under a dissecting microscope. We find the typical number, 

 viz., 10 pairs. The ist pair (PI. 3, fig. i, i) lies in the soft 

 skin between the epimera of pro and mesothorax close outside 

 the basis of the anterior coxa;, and these spiracles are larger than 

 all the others. The 2nd pair (2) is found behind the epimeron 

 of the mesothorax close before the circumflexed anterior end of the 

 metanotum and is smaller than the foregoing pair and somewhat 

 larger than the following pairs. The 3rd pair (3), almost belon- 

 ging to the metathorax, is situated in the membranous skin outside 

 its epimera and close before the anterior margin of the circum- 

 flexed ist abdominal tergite. The 4th pair (4) is situated in 

 the membrane outside the sternite of the 2nd segment close to 

 its anterior margin and is hidden by the marginal portion of the 

 tergite of the same segment. The following pairs are (as the 4th) 

 found in the above mentioned membranous pleura close outside 

 the sternites of the concerned segments and a little behind their 

 anterior margin, but are overlapped in a double way: firstly the 

 pleuron with the spiracle being overlapped, as mentioned before, 

 by the tergite of the same segment, secondly the sternite of the 

 foregoing segment with its posterior portion overlaps the anterior 

 part of the sternite and ventral portion of the tergite of the con- 

 cerned segment; thus f. inst. the 3rd abdominal spiracle (the 5th, 

 Avhen all are counted) is found as shown in fig. i (PI. 3) near 

 the posterior margin of the 2nd sternite (the place is indicated 5). 

 The last spiracle in the female belongs to the first one of the 

 (2) shortened and overlapped segments and it is found quite on 

 the same place as the other. — The spiracles are oblong and 

 do not seem to present peculiarities; their structure and mecha- 

 nism for closing I have, however, not examined more closely. 

 From each tracheal chamber inside the spiracle goes a longitu- 

 dinal tracheal stem to the chamber of the foregoing spiracle ; the 

 other stems 1 have not examined. 



