68 Annals Entomological Society of America [Vol. Ill, 



male, which was quite lost to view, only the hind legs projecting 

 beneath the abdomen of the female. The pair in copulation was 

 observed never to feed, mo\ing about as one insect; and anoma- 

 lous as it appears, the mcml)er on the ventral side, the male, con- 

 tributed no effort in the locomotion during the nuptial wander- 

 ings. His fore and middle legs doubled under the sternum, the 

 hind pair extending stiffly as though paralyzed beneath the 

 abdomen, where they were held securely by the tarsal sjDurs of 

 the female interlocking with the tibial spines of the male. 



The locomotory function was accomplished by the female, the 

 front and middle legs of which were used freely in walking; by 

 releasing temporarily the entwining spines of the hind legs she 

 was able to leap at will. In this manner, the female moved 

 about on the body of the host as though unhampered by its 

 anchored mate. 



Seven pairs of these fleas were collected from the live squirrel 

 with the aid of a camel's hair brush, placed in cell slides and 

 co\'ered with glass slips. They were observed under the low 

 power microscope, then kept in separate vials, one to se\-eral 

 hours until the function was completed. 



As observed microscopically, the male adheres to the female 

 by the pseudo-joints of the terminal segment of the antennae. 

 This attached appendage is extended and pendant, interlocking 

 by its hairs the bristles on the \^entral side of the second abdomi- 

 nal segment of the female. The hind femora of the latter grasps 

 the male by the head at a point anterior to the antennal groove. 

 The head of the male is held in position between the inner sides 

 of the meta- femora of the female. The tarsal spurs of the female 

 entangle the spines of the hind tibia of the male. The smaller of 

 the pair thus suspended assumes the passive role moving at the 

 volition of the female. 



The copulatory act is manifested in the male by the watch- 

 spring like action of the spiral, which, coiling and uncoiling inter- 

 mittently extends and withdraws the terminal apparatus. 



The male claspers are seen on either side of the vaginal groo\-e 

 of the female directly below the anal flap. The male makes a dis- 

 tinct concavity in the caudal portion of the back ; with the strong 

 action of the muscle attachments the plate of the penis is made 

 very elastic. The spasmodic pulsations of the curled up abdomen 

 are followed by a current of bubbles j^assing through the genitalia 

 of the male upwards to the female. The spermathcca of the latter 



