704 PROCEEDIXGS OF THE NATIONAL MUSEUM. vol. xxvii. 



the margin on either side of the tooth distinetl}' serrulate, with 

 spinules arising- singly between the serrulations. Mental setai 3 each 

 side, with an irregular transverse band of smaller ones across the mid- 

 dle. Lateral setie 8. Hook rather short, stout at base, rapidly taper- 

 ing- to a slender incurved point. Teeth on opposed margins of lateral 

 lobes small, becoming obsolete at the inner angle, slightly hooked, 

 each armed with one or two short spinules. 



Thorax slightly compressed, high. Legs slender, hairy. Wing 

 cases reaching the l)ase of the seventh abdominal segment. 



Al)domen triquetral, the sides nearly apparallel as far as the eighth 

 segment. Lateral spines on segments 8 and 1>, straight, sharp, spinose 

 on external margin. Dorsal hooks on segments 4-7, long, straight, 

 sharp, slightly declined at apex, decreasing in size anteriorly w^here 

 hidden between the wings, with spinose superior margins. Append- 

 ages very long and slender, as long as the last three segments of the 

 abdomen together; laterals two-fifths as long as the others, all thinly 

 fringed with tawny hairs. Segment 1() exserted, more than twice as 

 long on the ventral side as on the dorsal. 



LIBELLULID gen.? sp..' 

 Plate XLI, fig8. 11, 12. 



Two small nymphs, apparently half grown. Length, 11 mm. 



Stock}", rather smooth of body, with short legs. 



Head of the type of Libellula, concave in front between the high, 

 narrow, verj^ prominent eyes, which are directed forward and are 

 situated l)efore the middle of the head. Sides of the head scarcely 

 narrow^ed before the broadl}" rounded hind angles. Rear marked 

 with longitudinal scars. Antennae pale with basal segments blackish. 

 Labium ample, median lobe prominent, with a wide obtuse middle 

 tooth, on either side of which the edge is strongly serrulate; stout 

 spinules arise singly between the serrulations; eleven mental seta3 

 each side, the seven outermost in a stronger series; nine lateral setae; 

 movable hook long, slender, straight to the incurved apex; teeth on 

 opposed margins about ten, strongh^ serrate, each armed with about 

 three or four graduated spinules. 



Legs pale, scantil}^ hairy; femora w^ith tw^o dark l)ands. 



Abdomen blackish with paler margins, smooth, depressed, possess- 

 ing- the merest rudiments of doi-sal hooks on segments 4 and 5, where 

 hidden between the wings. There are very short bare lateral spines 

 on segments 8 and 9, one-fifth the length of their respective segments. 

 Segment 9 very strongly concave on its apical dorsal margin, less 

 than half as long on middorsal as on midventral line. Tenth segment 

 annular, included in the apex of the ninth. Appendages short, hardly 

 longer than the ninth segment on its ventral side, triangular, j'ellow- 

 ish, with black bases; laterals one-third as long as the others. Seg- 



