
630 THE AMERICAN NATURALIST. [VoL. XXXVI. 
(a, 6, Fig. 18). Such a case is shown in Fig. 17. The cross 
vein in the basal part of the subcostal space, said by some 
to be absent in Sisyra, was present in every specimen. The 
other variations seen were in the number of cross veins between 
KA: and R2, which is normally three. In two cases four were 
present and in one other instance there were five. But these 
were all of a nature easily explainable, as there were two or 
three faint veins standing close together, showing that the 
material usually forming one vein had formed several. Between 
Rz and R3, the only other space showing any variation, the 

Fic. 18. — Diagram of variation in wing veins, illustrating the table. 
normal number is one. In seven cases there were two, in one 
three, and in one four. The same tendency to have several 
weak veins close together was shown here. All the added 
cross veins were on the proximal side of the normal one. The 
variation in cross veins seems to have no connection with that 
in the tips. The specimen having the most erratic form of tip 
(9, Fig. 18), which occurred only once, had the cross veins 
entirely normal. 
SUMMARY. 
The points of chief interest developing from this study may 
be summarized as follows : 
1. In Sisyra the mouth parts are not in the usual opposed 
position, but are approximated in pairs to form two sucking 
tubes, excessively elongated, and decurved. 
2. The brain is in the prothorax in old larvae. 
3. The stomach has no posterior opening in the larva. 
