\'ol. XXvi) ENTOMOLOGICAL NEWS 393 



from the gut and from each other than is actually the case. The true 

 relative positions may be learned by comparing this figure with figure 

 1 of Plate XV'll. The origins of the various branch -tracheae and 

 tfi' visions to the most minute branches have been indicated as 

 i>otsible from the sections. The tracheae which do not lie 

 u(>on the gut wall or do not enter the rectal folds have not been shown 

 farther than ihort distances from their origins, even though they may 

 lie dorsad or vcntrad to the gut; this for the sake of avoiding con- 

 fusion. The only exceptions to this statement are in the cases of the 

 tracheae which uke part in the anastomosis (anai) mid-ventral to the 

 rectnm in abdomiiwl mti o Hut X ; these tracheae are indicated by lines 

 of dashes alternating with dou, thus — . — . — . — . Of the tracheae 

 which supply the rectal walls, those which run on the dorsal surface or 

 enter the dorsal longitudinal fold are shown in solid lines ; those which 

 run on the ventral surface or enter the lateral rectal folds are shown in 

 broken lines, thus , as soon as they cross the outlines of the gut. 



In one respect this diagram departs from the conditions shown in 

 the sections of larva no. 7. In those sections the right bteral trachea 

 (rll) becomes much smaller in aMominal segment VII than its fellow 

 of the left side and disappears as several minute tracheae before con- 

 necting again with the docaal trachea. This, after comparison with 

 other larvae, appears to be an anomaly, so that the right lateral trachea 

 is here represented as beinf similar to. but not identical with, the left 

 lateral. The branch tracheae nv. r/rfi. which on the right side of the 

 diagram come from the dorsal longitudinal trachea, are exactly as in 

 the sections, although the corresponding tracheae hv, Urit, on the left 

 side come from the lateral longitudinal trachea. This difTerence in the 

 two sides of larva no. 7 may be due to the atrophy of the right lateral 

 longitudinal trachea just mentioned. Compare, however, the same 

 tracheae in text-figure I. pace 388. The right lateral trachea u ^es- 

 rni in the sectMMis from its point of separation from the right dorsal 

 in the anterior part of segment VIII as represented in the diagram. 



The figures 1-9 on the left side of this plate indicate the levels of the 

 first section of each slide. 1-9 respectivelr- 



PUT« XVII. fig. I. Part of photograph of section 18. row i. slide 

 6. of the author's series of sections of TkmumUontura larva no. 7 9. 

 made with Leitz oc. 4. obj. 3. by Mr. H. A. Walters. The section is 

 viewed from its anterior surface, x 72.5. 



AhhreviaHon4 Vstd in Plates XV-XVII. 



at -¥ f, outline of alimentary canal and superimposed fat masses : in 

 PUte XV it corresponds also very nearly to the lateral edges of the 

 stemites. 



ON. antennal nerxe. 



anas, anastomosis of tracheae in abdominal segment X. 



at. antennal trachea. 



