Zool.-Vol. I.] CALVERT— ODONATA. 415 



length from before backwards. Alternating with these 

 eight larger folds are usually one or two teeth .018-. 025 

 mm. long, these teeth thus corresponding to the eight small 

 folds of Argia. 



In Ischnura Ramburii var. credula, the eight large folds 

 are .26 mm. long and bear fourteen to eighteen teeth 

 .015— .02 mm. long. The eight small folds are represented 

 by shorter patches covered with minute granulations but 

 without teeth. 



For Anax Junius and Herfietogom-phus elafis my results 

 agree completely with Dr. Ris' for the subfamilies ^Es'ch- 

 ninas and Gomphinas. The chitinous coat of the gizzard 

 is covered with minute granulations, without differentiation 

 into fields, which likewise extend throughout a very con- 

 siderable part of the foregut. 



A similar granulation exists in the gizzard of the Libel- 

 lulinas, but with this difference, that it is denser immedi- 

 ately surrounding the four "tolerably thin, translucent, 

 chitinous platelets with irregular contours" which take the 

 place of the teeth of the larval gizzard in this subfamily. 

 These chitinous platelets are visible to the naked eye in the 

 preparations, being often 1.5 mm. in length or longer. 

 As Dr. Ris pointed out, they are bilaterally symmetrical in 

 their arrangement and their shape. I have found differ- 

 ences to exist in their relative lengths and widths which I 

 here place on record, although it would be rash to assume 

 that these particulars represent specific or generic charac- 

 ters until a larger number of individuals have been studied. 



As to length, all four platelets were found to be approx"- 

 imately equal in Pantala hymencea and Pseudoleon suferbus, 

 the ventral pair somewhat longer, than the dorsal pair in 

 Trained onus/a, Dythemis sterilis and Micrathyria Hageni, 

 shorter than the dorsal pair in Orthemis ferruginea and 

 Diplax corricftta. The ventral pair were found distinctly 

 broader posteriorly than anteriorly in Panlala hymencea, 

 Pseudoleon sufterbus and Di^plax corru^pta, tapering and 

 pointed posteriorly in Tramea onusta, Orthemis ferruginea, 

 Dythemis sterilis and Micrathyria Hageni. 



