78 PROCEEDINGS OF THE ACADEMY OF [March, 



Some distance anterior to the origin of the dorsal rectal tracheae 

 there arises, on each side, the right lateral rectal trachea, rlrtu and 

 the left lateral rectal trachea llrti, from the right visceral trachea 

 and left visceral trachea respectively, at a point just mesad of the 

 origin of each visceral trachea from the lateral trachea. The right 

 lateral rectal trachea extends cauclad and sends branches cephalad 

 and caudad which enter the right longitudinal rectal fold. In like 

 manner the left lateral rectal trachea supplies the left longitudinal 

 rectal fold (Fig. 1). 



Toward the end of the ninth segment a dorsal trachea appears, 

 Idrtw This originates from the left median caudal gill trachea, 

 Imcgt, at the end of the ninth segment. It sends a branch caudad 

 which penetrates the rectal epithelium in the anterior part of the 

 tenth segment. Another branch extends cephalad giving off branches 

 and penetrates the rectal epithelium about the middle of the ninth 

 segment. No trachea corresponding to Idrtn, appears on the right 

 side. Toward the end of the ninth segment small trachese are 

 noticed in the spongy masses between the longitudinal folds of the 

 rectum. The trachea in the ventral mass originates from a 

 branch of the left lateral trachea at the hind end of the ninth seg- 

 ment. This little trachea extends mesad and cephalad and disap- 

 pears in the ventral spongy mass about the middle of the ninth 

 segment. The trachea of the left spongy mass originates at the 

 end of the ninth segment from the left dorsal rectal trachea Idrtu. 

 It runs cephalad a very short distance and disappears in the left 

 spongy mass. The trachea of the right spong}^ mass originates 

 at the end of the ninth segment from the right median caudal gill 

 trachea, rmcgt. It extends mesad and cephalad a short distance in 

 the right spongy mass where it disappears. 



At the end of the ninth and the beginning of the tenth segment 

 there is an anastomosis between the right and left lateral longitudinal 

 trachese which meet in the midventral line. Two other trachese 

 also take part in this anastomosis. These are a branch from the 

 right and a branch from the left lateral caudal gill trachese, rcgt 

 and Icgt, respectively. 



"Observation and experiment with carmine particles on living 

 larvae of Argia moesta putrida from the vicinity of Philadelphia 

 showed that a larva watched for two hours may give no sign of 

 rythmic rectal contractions, but that these may suddenly begin 

 and then continue for varying periods. They consisted of sets of 

 three rapidly successive contractions, every third contraction being 



