86 Proceedings of the Biological Society of Washington . 



Base of distal segment fully as long as unguis 4 



4. Dorsum with five rows of plate like structures . . lestudinatus Thorn. 

 Dorsum with three rows of plate like structures . . japonicus Baker. 



Chaitophorus aceris (Linn.). 



The dimorph of this species is easily separated from that of other spe- 

 cies by the long prominent hairs with which this species is armed. These 

 are found in a row about the margin, consisting of about 28 hairs and in 

 two median rows on the dorsum of about 8 hairs each. The antennae 

 are armed with one or two long hairs. Average measurements are as 

 follows: Antennal segment I, 0.032 mm.; Segment II, 0.032 mm., little 

 more than half as thick as Segment I. Segment III, 0.112 mm., armed 

 with at least one long hair nearly as long as the Segment. Segment IV, 

 (0.032 mm. -f 0.112 mm.) Length of body hairs about 0.272 mm. 

 Length from vertex to tip of cauda 0.072 mm. Described from specimens 

 taken by Theo. Pergande at Stettin, Prussia, July 26, 1898. It should be 

 noted that in some of the literature dealing with dimorphic forms the 

 lamellate dimorph of testudinatus is described under aceris. 



Chaitophorus americanus Baker. 



This species was described by the author from material collected by 

 Dr. Edith M. Patch at Orono, Maine, June 15, 1909, on Acer dasycarpum. 

 It can be distinguished from other lamellate species by the very long 

 antennae and the length of the unguis of the distal segment. About the 

 margin of the thorax and abdomen there are about twenty-four lamellae. 

 Those on the lateral margin of the abdomen are rather broad, whereas 

 those upon the thorax are narrow and those upon the caudal extremity 

 are also. The first antennal segment is armed with a large protuberance 

 nearly as long as the segment is thick. This extends forward toward the 

 vertex. Average measurements are as follows: Segment I, 0.032 mm.; 

 II, 0.02 mm. ; III, 0.144 mm. ; IV (0.048 mm. + 0.192 mm.). Largest 

 lamellae about 0.064 mm. long. Length from vertex to tip of cauda, 

 0.592 mm. 



Chaitophorus japonicus, n. sp. 



Specimens of this species were received from Francis Windle, West 

 Chester, Pa., through the Federal Horticultural Board. They were col- 

 lected on May 19th, 1916, from a Japanese maple. At first it was thought 

 that these were specimens of tesludinatus, but a careful examination 

 showed that the dorsal sculpturing is entirely different. In this species 

 there is a central longitudinal row of plates and on each side of this a row 

 of wide, short plates which extend from the median row to the margin, 

 making in all three longitudinal rows, as compared to the five rows met 

 with in testudinatus. The margin is armed with about 20 lamellae on 

 the abdomen and thorax and these are broadly rounded. Those on the 

 vertex are similar in shape. The first antennal segment lacks the large 

 projection met with in americanus. Average measurements are as fol- 



