BY R. J. TILLYARD. 405 



found the explanation of the remarkable difference in size 

 between the larvae of (' . pijcfmira and (' . tnonfftna, a difference 

 quite unwarranted by the small difference of size in the 

 imagines. For the larva of the latter, having no fear of 

 Aesrhn'ul larva, can feed up and develop rapidly, and so 

 attain a much larger size. 



The full-fed larva of C. mniifniKt (Plate xi., fig. 1) differs 

 principally from that of ('. pygnura in the following points. 



1. The great length of its forelegs. These are fore- 

 shortened in the plate, as the insect sits with the femur and 

 tibia bent up at an acute angle. The actual measurements 

 are : femur, 4-7, tibia 4-8, tarsus 2-5 mm. For the middle 

 leg, the corresponding measurements are 6, 5, 2-5 mm. ; and 

 for the hind leg, which is also extremely long, 7, 6, 3-2 mm. 



2. In the labium (Plate xi., fig. 2) the dentition of the 

 r'Kjht lateral lobe is similar to that of the left in (\ pygmfea, 

 and vice versa. This is not important, however, as I have 

 only examined two larvae of ('. i/ionfnna, and the character 

 may not be constant. 



3. In the labium also, there is a peculiar development of 

 double mental setae, which I have not observed elsewhere. 

 In the figure, for example, there are thirteen mental setae on 

 each side ; but, on the right side, two pairs are grouped 

 together so as to touch from their bases upwards. If these 

 had coalesced, we should have had eleven setae, the number 

 found in (J . pygmaa. 



4. The greater size of the larva, whose total length is 17 

 mm., compared with 14 mm. for ('. pyyuicra, and corres- 

 pondingly larger in all parts. 



Striirtitre of tJte Larval Gizzard (Plate xi., fig. 5). 



This is essentially of the Libellnlid type, with four fields 

 shewing bilateral symmetry. A comparison with the gizzard 

 of Synfhemis eusfalarfa ("Monograph of the genus Syn- 

 t/iei/iis," fig. 2, p. 326) shews two important differences. 



