250 NEW YORK STATE MUSEUM 
But we are here concerned only with giving a simple ac- 
count of what this accessory genital apparatus, developed upon 
the 2d and 3d abdominal segments of the male, consists of, 
and how it compares in different genera of dragon flies. As 
already, Stated). the receptacle fon athe: ssperniesS tne mayesicles 
situated at the front of the sternum of the 3d segment in the 
median line, and visible externally as a rounded prominence. 
ihe orsan for thes transierenceon the mcontentsmonuunemvestele 
to the bursa copulatrix of the female is a median, unpaired, 
jointed and retractile intromittent organ, the penis. This is 
situated directly in front of the vesicle, on the sternum of the 
second segment, and is more or less directly connected with 
the vesicle. Vesicle and penis are the direct agents of sperm 
Fig. 17 Male abdominal appendages of the dragon fy Edonis helena Ndm. 1, 2, 
3 the three basal abdominal segments and their appendages, inverted and viewed from the 
side; v vesicle; gl genital lobe; # hamule; al anterior lamina, in both lateral and ventral 
views; ¢ tip of the abdomen less enlarged, segments 7 to 10, and appendages 
itransterences) but thence eanen. Olney spantsmaccessOnyvamtoumt inert 
function. Beside the penis are one or two pairs of hamules, 
that assist in maintaining proper positions in copulation. 
KOK UNS SMS WES MISES CM We suenAwIN O ne Ad 
segment a more or less prominent, chitinized, concave arching 
plate, the sheath of the penis, doubtless with a protective 
function. All these, and other parts yet to be mentioned, are 
developments from the sternum: and in the family Libel- 
lulidae, the tergum also contributes by the development of the 
well known “ genital lobes” from its postero-lateral angles of the 
2d segment. ‘These parts are externally visible. Their general 
appearance is shown in figure 5, in a case in which but a single pair 
ef hamules is developed. It will be seen that these parts cover only 
the posterior part of the sternum of the 2d segment, and a bit of 
the front of the sternum of the 3d segment. It was doubtless in 
the hollow between these two segments, in the reentrant angle 
