Vol. XXvi) ENTOMOLOGICAL NEWS 389 



branch, the dorsal rectal trachea, (rdrti, tdrti), which runs mesad and 

 enters the cavity of the dorsal longitudinal rectal fold. Within this 

 fold thi« trachea divides and subdivides, but no anastomosis between 

 atv mallest subdivisions of the right dorsal recul trachea with 



sui of the left dorsal rectal trach«a have been found, in spite 



of special search for them. 



A short distance anterior to the origin of each dorsal rectal trachea 

 a lateral rectal trachea (rlrti, llrti). arises, either indirectly from the 

 dorsal longitudinal trachea (cf. text-figure i and right side of Plate 

 XVI). or from the lateral longitudinal trachea (r/. left side of the 

 sai! . which extends mesad and caudad and enters the lateral 



Ion rectal fold of the same side of the viscus, within which 



it sutxiivuies. A smaller, posterior, tracheal supply (r/rlii, Urtii) 

 is also received by these lateral rectal folds from branches either from 

 the lateral lonKiiudinal trachea or from the median caudal gill trachea. 

 as may be seen by comparing the right and left sides respectively of 

 Plate .\VI. No anastomoacs of tracbeolcs frum the anterior supply 

 itf the lateral rectal folds with tboae of the posterior supply have been 

 detected. 



A small poaterior tradical snppiy for the dorsal rectal fold is re- 

 ceived from the right and left nie<iian caudal gill tracheae (tracheae 

 rdriit, Irditi ui Plate XVI). Here afcain no aaastonioaes, either trans- 

 verse or longttndiittl, have been found. 



The only ■milomoiinc irachwt wWdi have been discovered are the 

 posterior ti imhiliimi of the right and left lateral longitudinal trach* 

 eae which, awaming a ventral position, meet on the mid-ventral line 

 vcntrad of the alimentary canal; in this anastomosis (amas) take part 

 also a branch from the right and a branch from the left lateral caudal 

 gill trachea. These four aoMtomoatng tracheae, since they lie ventrad 

 to the rectum, have been repreacated by lines of alternating dots and 

 dasher in llate XVI. A similar anaatomotis in Mecistoga^ter tmodestus 

 has been figured* in No. Ill of these studies and has been found by the 

 writer in traus|>arrnt living larvae of Hetaerma oaimraiui, Argia 

 moetta putrida and IscHnura ferticalis: it has not been figured for 

 Anisopterous larvae and may prove to be a characteristic of those of 

 the Z yg ogKr a . 



A comparison of the works of authors who have described the trach- 

 eae of Odonate larvae has yielded the table on page 390. 



The ttrmdmal troeheoles, of the tracheae which run into the longi- 

 tudinal rectal folds, enter the epithelium, although whether they mere- 

 ly pass between the epithelial cells or actually penetrate the latter, the 

 conditioa of the ma ter ia l does not enable one to decide. The diameter 

 of some of these infra-epithelial tracheoles, near their point of final 



*Ent Newt, xxii, pL xvti. fig. 7. 1911. 



