1863.] 
261 
meister and Vander Linden actually annexed the troublesome genus 
Cordulegaster to ..'Esclinina, so as to cut the knot instead of untying 
it, although, as M. Selys well observes, that genus has manifestly the 
general characters and the coloration of Gromphina, and in some of its 
subgenera the eyes do not quite touch. I have endeavored—I know 
not with what success—to define with precision wherein the distinction 
between the eyes of G^omphina and ^schnina consists. In the exotic 
genus Petalia, which belongs to Gomphina, the eyes touch, but the 
touching part is figured as scarcely angulated, especially in the sub¬ 
genus Phyllopetalia. (Mon. Gomph. Plate 18, figs. 7 and 8.) So far 
as TVi A. genera are concerned, the distinction laid down in the Table 
is undoubtedly correct. — In the Tribe Libellulina there are often 
one or two supernumerary cross-veins in the 1st or 2nd series of 
antecubitals, either in the middle or at the tip of the series, which of 
course cannot “correspond” with any cross-veins in the other series; 
but the other cross-veins always “correspond,” i. e. are not “dislocated” 
as Say expressively terms it in Hymenoptera. In the tribe ^schnina 
they are all “dislocated” except at the base and a single robust pair 
not far from the base. 
SIALINA. 
SiALis iNFUMATA Newm. From the re¬ 
cent specimen. A terminal abdominal^ 
joints ^, seen from above and slightly 
' ^ magnified; a 8th dorsal joint, d penis.— 
<2- B. The same, seen in profile, a 8th dor¬ 
sal joint, h anus? c genital booklet 
(one only.) d penis.— C. Genital booklet, much magnified.—D. Penis, much 
magnified, seen from above and straightened out. 
Note 25, p. 180. The above drawing represents the position assumed 
by the parts when the middle of the abdomen is slightly compressed. 
The last ventral, to the tip of which the genital booklet (c) is attached, 
when viewed from below has on each side of its disk a large round fo¬ 
vea, and underneath the lobed tip (5) of the 7th ventral is a very 
large triangular cavity directed forwards, which is probably the anus. 
The whole is black, except the booklet which is piceous but paler at 
base and tip. I am not certain whether the piece succeeding a is to 
be considered as a ninth dorsal or as the basal joint of the penis, but 
