326 



MONOGRAPH OF THE GENUS SYNTHEMIS, 



as it were, in half-profile. In each of the two inner* folds will 

 be found two large sharply hooked teeth; in each of the two outer 

 ones, there is a thick single tooth, also sharply hooked, but with 



Rjr 



Fig.2— Larval gizzard of Synthemis eustalacta(x 25). 



a strong outer lateral edge carrying four or five small serrate 

 teeth, and indications of two very small serrations on the inner 

 lateral edge. For comparison, I examined the gizzards of two 

 other CordtUiiie}sirvse, Gordulephya jyygmcea and Hemicordulia 

 tau; and one J^Libelluliiie larva, Orlhelriun caledonicum. They 

 are all almost exactly like that of Synthemis eustalacta, the only 

 difference being in tlie number of small serrations along the 

 edges of the singlejtooth. This is a very interesting result, for 

 it proves, beyond all doubt, that the larva of Synthemis, though 

 so closely allied to that of C or duleg aster, is still of the true 

 Libellulid stock. 



Another point of great interest is that in the larva of Cordide- 

 gaster, although the ^Eschnid radial symmetry is already estab- 

 lished, yet the dentition in each of the four " folds " is very much 

 like that of the two outer folds in Synthemis, viz., a single 

 strong tooth with a serrate edge. This is very unlike the denti- 

 tion in any other J^schnid group so far examined; in all of which 



* The terms " inner " and " outer " refer only to the diagram; the line of 

 section might have been taken in a diametrically opposite position, and 

 then the positions would have been reversed; or another cutting might have 

 given us one pair on each side. 



