PERGANDE NORTH AMERICAN PHYLLOXERIN^. 20I 



convex and more prominent above than beneath, with a rather 

 deep dimple or depression at the centre, which depression occa- 

 sionally reaches as far down as to the opposite side of the gall ; 

 its basal circumference forms either a depressed or elevated ring. 

 Beneath they are but slightly convex, often sunken below the 

 plane of the leaf, with the centre depressed and bearing a very 

 short, somewhat conical nipple, which is tightly closed and densely 

 covered on the inside with a pale pubescence in the younger galls, 

 whereas in the older or mature galls the nipple splits into 4-8, 

 or rarely more, short and rather flat recurved bracts, which leave 

 a round or slightly oval orifice between them. 



In the largest and perfectly developed galls the upper side is 

 either of a delicate pale red with the dimple darker and its basal 

 circumference yellowish-green ; or entirely yellowish-green with 

 only the dimple of a beautiful pink color. Beneath they are 

 uniformly yellowish-green, often with a faint reddish tinge, 

 especially toward the nipple. On the other trees, most densely 

 covered by tljem, they were less beautiful, with less red and a 

 shallower dimple. The walls are very thin and paper-like and 

 readily collapse when old. All galls are perfectly smooth on both 

 sides. 



Stem-mother. — One of the smallest so far observed. Length 

 0.4-0.6™™- Broadly ovoid, pointed posteriorly. Color yellow or 

 pale orange. Antennae and legs dusky, eyes black. Antennae 

 very short, the third joint being scarcely longer than the two 

 basal joints combined, and rather thin ; joint i much the stoutest, 

 about as long as wide, and truncated at apex ; joint 2 longer than 

 wide, stoutest and rounded at apex ; joint 3 slender, somewhat 

 curved, with 8-10 irregular and coarse annulations; the thumb 

 short but distinctly projecting ; two to three fine hairs surround- 

 ing the tip. Front of head straight or slightly concave. 

 Granulation of body extremely fine and quite dense. 



Kgg. — White, with a faint yellowish tinge, regularly ovoid, 

 highly polished and quite profusely reticulate. 



Larva. — White; legs and antennae pale dusky; eyes red. 

 Six prominent conical tubercles along the front edge of head, 

 each furnished with a fine hair. Surface of body finely granulate. 

 Antennae longer than usual, the third joint stoutest at middle, 



