Vol. 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 

 i of Plate XVII. The origins of the various branch-tracheae and 

 their subdivisions to the most minute branches have been, indicated as 

 exactly as possible from the sections. The tracheae which do not lie 

 upon the gut wall or do not enter the rectal folds have not been shown 

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

 lie dorsad or ventrad 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 take part in the anastomosis (anas) mid-ventral to the 

 rectum in abdominal segment X ; these tracheae are indicated by lines 

 of dashes alternating with dots, 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 lateral trachea 

 (rlt) becomes much smaller in abdominal segment VII than its fellow 

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

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

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

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

 lateral. The branch tracheae rvs, rlrti, which on the right side of the 

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

 the sections, although the corresponding tracheae k's, llrti, on the left 

 side come from the lateral longitudinal trachea. This difference 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, page 388. The right lateral trachea is pres- 

 ent in the sections 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 respectively. 



PLATE XVII, fig. I. Part of photograph of section 18, row i, slide 

 6, of the author's series of sections of Thaumatoncura 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. 



Abbreviations Used in Plates Xl'-XJ'II. 



ac + /, outline of alimentary canal and superimposed fat masses ; in 

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

 sternites. 



an, antennal nerve. 



anas, anastomosis of tracheae in abdominal segment X. 



at, antennal trachea. 



