140 
Psyche 
[December 
the mandible. In the left mandible, the molars form a 
cutting edge parallel to that of the incisors, with a sharp 
tooth at each end and 5 small intermediate teeth (PI. 13, 
fig. 6). In the right mandible, the molar region is reduced 
to a single, independent, sharp tooth; the first incisor has 
a small basal tooth (PI. 13, fig. 5). A muscle can be seen 
attached to the molar region of the left mandible, in- 
dicating that the molars are probably capable of indepen- 
dent movement; exact information must await study of 
properly fixed material. 
Mesothoracic wingpads extend to the posterior margin 
of 2nd abdominal segment, 1.8 mm. long. The nymph is 
too young and the fixation too poor to identify it by wing 
venation. It is interesting to note that the thoracic spiracles 
are not open or functional. Peritreme and trachea present, 
but lips sealed together, as found normally in aquatic 
forms. Legs short, densely covered with long, simple 
setae (PI. 14, fig. 3). Femora compressed, incrassate; 
length of left prothoracic femur 1.1 mm., mesothoracic 
femur 1.9 mm., metothoracic femur 2.8 mm. Both femora 
and tibia are heavily ridged, and are, as a consequence, 
almost rectangular in cross-section. Tarsi slender, very 
short, each with a well developed pair of claws. Abdomen 
short and thick, round in cross-section, maximum width 
of 3rd segment 2.1 mm., covered with heavy setae. Pro- 
ventriculus primitive, generalized, with 16 well-defined 
folds, 8 major (7-9 teeth) and 8 minor (5-6 teeth), plus 
16 anterior, half-length folds (2-4 teeth) which alternate 
between the regular folds (PI. 13, fig. 7). 
Caudal gills one-jointed, of the saccular triquetroquad- 
rate type (PI. 14, figs. 1, 4). Median gill quadrangular, 
but somewhat flattened in the horizontal plane, 2.3 mm. 
Explanation of Plate 13 
Megapodagrionid nymph, Ciu, New Caledonia. Fig. 1, dorsal view 
of labium. Fig. 2, detail of right lateral lobe of labium. Fig. 3, dorsal 
aspect of nymphal head. Fig. 4, right maxilla. Fig. 5, left mandible. 
Fig. 6, right mandible. Fig. 7, diagram of several dental folds of pro- 
ventriculus to show generalized pattern. 
Magnification. Figs. 1, 3 (*20). Figs. 2, 4-7 (x40). 
