August, '17] BAKER: EASTERN APHIDS, PART II 429 



occur in Europe and two in America. The European species are 

 aceris L. and testudinatus Thorn. Of these the latter species has 

 dimorphs margined ^vith lamellae whereas the dimorphs of aceris 

 are armed onlj^ with long stout hairs. The two species in this country 

 negundinis Thos., and the present one both have dimorphs margined 

 with lamellae. Negundinis is found upon the Manitoba maple 

 (Acernegundo) , whereas americanus feeds on the trees mentioned pre- 

 viously. The two species are easily distinguished. 



Alate Viviparous Female: Morphological Characters: Antennae showing con- 

 siderable variation, but being about as follows: Segment III, 0.72 mm.; IV, 0.44 mm.; 

 V, 0.34 mm.; VI (0.128 mm. + 0.368 mm.). Segment III, armed with from 18 to 

 24 irregularly placed sensoria which often give the segment a more or less swollen 

 appearance. Antennal hairs long and prominent; about 0.16 mm. on Segment III. 

 Cornicles about, 0.24 mm. long and covered with reticulate areas; length from vertex 

 to tip of Cauda 3.1 mm. 



Color Characters: General color dark green. Head, antennae, thoracic lobes, 

 sternal plate and cornicles black. Abdomen with a row of transverse black bands on 

 the dorsum and with a row of more or less circular black spots along the margin. 



Dimorph: Morphological Characters: Antennal segments as follows: III, 0.16 

 mm.; IV (0.064 mm. + 0.24 mm.). First segment large, projecting forward; vertex 

 and entire margin of the body with the exception of the lateral margins of the head 

 covered with a row of lamella;. On the lateral margins of the head the lam^Use are 

 replaced by lanceolate spines. Similar spines also occur upon the outer margins of 

 the legs; dorsum apparently without plate-like structures. 



Color Characters: Pale greenish with red-brown ej-es. 



Described from specimens in balsam mounts. Type in U. S. 

 National Museum. Cat. No. 20345. 



Chaitophorus viminalis Mon. (1879, p. 31.) Taken on Populus 

 grandidentata, New Haven, Conn., June 29, 1914, by M. P. Zappe. 

 Conn. No. 1-16/24. 



A study of the type of this species kmclly sent to the writer by 

 Mr. J. J. Davis, and numerous specimens from different localities 

 proves that the species always possesses a granular surface on the 

 skin, although this granulation varies considerably in degree. The 

 color also varies from a light green to a dark brown. 



Chaitophorus nigrce Oest. (1887, p. 40.) Taken on willow at 

 Galesville, Conn., July 15, 1909, by B. H. Walden. Conn. No. 

 1-16/125. 



In studjdng a series of specimens thought to be this species it was 

 noted that the reticulate marking of the skin was a constant character. 

 Professor Oestlund kindly examined his type and informed the writer 

 that this character is present in the type. It seems, therefore, that 

 nigrce may be separated from viminalis on this character and on the 

 sensoria. The type of cordata Wms., proves it to be the same species. 



Chaitophorus hruneri Wms. (1910, p. 25.) Taken on poplar, 



