\'Ol. XXviJ BNTOliOLOGICAL NEWS 387 



•ophagns is marked by two longitudinal streaks of blackish pigment 

 corresponding to the areas of contact with the right and left dorsal 

 tracheal trunks. At mid-length of the oesophagus, at the level of the 

 hind margin of the head, it, on each lateral surface, right and left, a 

 salwary ^Uuul with a delicate duct running cephalad. The gizsard lies 

 i'1 ' ' xl o min a l segment : it* duttoous armaturr, in larva no. 4. con- 



M« tn kMgitadinal folds, cad? of which bears chitinous teeth. 



In eight of tlicac folds the teeth, near the posterior end. tend to m- 

 crease from one to two rows, while in the other alternating eight folds 

 the teeth are arranged in a single row throughout. The teeth of the 

 various folds are subequal in size, but in each fold tend to become 

 larger candad. The formula for the gizzard armature may be written 

 ^ (F 14-17. i Ii-I4>* The hind end nf the slomack and the place of 

 attachment of the ifal^gkiam tubes lie near the articulation of the 

 fifth and sixth abdominal segments. The iUtnm extends to the seventh 

 segment. 



The rectal epithelium presents three longitudinal folds, one which is 

 dorsal and a little to the left of the median plane, a second is left 

 latero-Tcntral, the third is right lateral Their relative positions may 

 l>c best seen in a cross-section of the rectum (PI. XVII. fig. 1). The 

 epithtfom is In ter rupt ed by three, longitudinal, thinner, pigmented 

 areas, one of which is nearlv nridventral (imfe) and Kes inunediatdy 

 to the right of the attachment of the left latero-vcntral fold, a second 

 irlp^) it immediately dorsal to the right lateral fold, the third illpa) 

 is to the left of the dorsal fold. Thete three pigmented areas are 

 homok>gous with the three **non-ccllutar hmgitudinal bands" of the 

 rectum of the larva of Uecistogaster modestusf and with similarly 

 placed band* in the recu of larvae of testes rectangularis. Argia 

 moesta putrida, A. Utomewf, Isekmmn vertUaHs. etc Both anterior 

 and posterior to the three longi tu dinal rectal folds in Tkaumatoneura 

 larva, the gut epithelium is very much thinner for its entire circum- 

 ference, efjualing. or nearly equaling, in thinness that of the three 

 longitudinal pik'Tnented areas, and containing also much pigment. 



Tracluoi System. The arrangement of the larger tracheae of the 

 dorsal side of the body b shown in Plate XV. It corresponds, except 

 in a few minor details, with our figitfe** for the tracheae of Meeistogas- 

 ter modestus larva and those of Colett and of Bervoetst for a larva of 

 "Agrion." The chief difference be t we en the present results and those 



•C/. Higgins. Prot Acad. Nat Sci. Phila. 1901. PP. 132. 133. 



t£nL News, xxii, pp. 452. 45J. pL xvii. fig. 10, 1910. The description 

 of them as "non-celhUar^ may not be justified when material in better 

 condition is examined. 



••Fnt News. xxii. pi. xvii. fig. 8. 1911. 



ttji>urn. Appl. Micros. & I^by. Meth. VI. pp. 2224-5. fig>- 7. 8- 1903. 



lAnnales Bk>I. Lacustre, VI. pp. §6. 17, ao, figs. 1-3. 1913- 



