272 E. T. CRESSON, JR. 



The stigma is that portion of the costal cell between the 

 apices of the auxiliary and first veins, and is often known as 

 the third costal section ; it is sometimes tinged with brown, 

 especially in certain groups. The fourth section just follows, 

 being that portion of the costa between the apices of the first 

 and second veins. The third section of the fourth vein is 

 that portion between the anterior and posterior cross-veins. 



For a satisfactory examination of these insects, especially 

 of the bristles, which are generally more like hairs than 

 bristles, a compound microscope is necessary, but not essen- 

 tial for determining most of the species as characterized in 

 the synopsis, except perhaps those of the subvirescens group, 

 which will give the most trouble in this respect. 



I have followed the recommendations of the Entomologi- 

 cal Congress in designating a single specimen as the type of 

 each species, but have called the remainder of the series 

 paratypes, as I do not favor the use of the much misused 

 term " cotype " when there is a type designated. The de- 

 scriptions are, of course, based upon the series which is com- 

 posed of the type and its paratypes. With the habitat of 

 each species I have given, in parentheses, after each locality, 

 the number and sex of specimens examined, followed by the 

 name of the collector and the collection possessing such 

 specimens. Where the name of the collector is not given, 

 the same is unknown, or is the owner of the collection. I 

 wish here to acknowledge my indebtedness to Mr. Banks for 

 his generosity in turning over his collection for my use, 

 these are designated "coll. Banks;" also to Mr. Johnson 

 who kindly loaned me the extensive New England material 

 in the collection of the Boston Society of Natural History 

 (" B. S. N. H") and from his own collection, "coll. John- 

 son." Those designated "A. N. S." are from the collection 

 at the Academy of Natural Sciences of Philadelphia. 



While on the subject it was thought that a synopsis, as 

 well as a bibliography and catalogue of the North American 

 species, would be useful to have under one cover, and would 

 be helpful to those students wishing to determine their own 

 material, and who have not access to the literature required. 

 The completeness of this synopsis is greatly hampered on 

 account of the limited amount of material at hand represent- 



