HANSEN AND SÖRENSEN, THE TARTARIDES- 19 



nites. The trunk of the »lung», when the rid ges named are con- 

 sidered the starting-point, has its lower wall very short, but 

 it is much expanded as a wing outwards along the lower part 

 of the thinner lateral skin on the side of abdomen. Seen on 

 a longitudinal vertical section the trunk is nearly trapezoidal, 

 miich higher than long, with the upper angle very acute, and 

 the long front side, the bottom of the trunk, sloping strongly 

 downwards and a little forwards, while the lower side, along 

 the sternite, is very short. At the origin from the trunk the 

 »pouches» are strongly chitinized, brown, so that the bottom 

 of the trunk looks as a lattice or a very oblong plate pierced 

 with exceedingly narrow, somewhat oblique slitsa 



The spirades of first pair are somewhat shorter (across 

 the animal) and, especially a t the inner end, distinctly broader 

 than the second just described; the two ridges do not show 

 any essential deviation. The trunk is not very different; seen 

 on a longitudinal vertical section it is still shorter along the 

 sternite, but its bottom is longer and vertical or even sloping 

 a little forwards. 



The Tartarides ha ve only one pair of »lungs», correspon- 

 ding with the first pair in Oxopoei; by an investigation of a 

 specimen cleaned with caustic potash no vestige of a second 

 pair or of any other respiratory organ could be found. Al- 

 ready Thorell has correctly seen the spirades in Trithyreus 

 Grassii Thor. The spirades are proportionately much shorter 

 than in Oxopoei; they are situated at the posterior margin 

 of the second sternite at a rather short distance from its lateral 

 margins. They are visible without manipulation as a trans- 

 verse or a little oblique, oblong oval or narrowly oval area, the 

 central oblong portion of which is deepened, while the posterior 

 börder is very slightly, the anterior börder more conspicuously, 

 raised above the surroundings ; the posterior margin itself of 

 the front half of the oval ring formed in the way described 

 is a more or less conspicuous brownish line. We ha ve studied 

 the »lungs» of tw^o specimens of Schizomus Simojiis n. sp., 

 one of t hem in the natural condition, the other cleaned in 

 caustic potash. The trunk (Pl. 1., fig. 1 q, a) is directed es- 



^ The ridges lim it ing the spirade being low and the margins of the 

 pouehes very conspicuously chitinized, the whole structnre conveys easily 

 the impression that the bottom of the short triuik is tiie spirade itself, 

 whicli thus seems to be lattice-shaped, with a very great nurnber of 

 cvossbars and transverse fissures. 



