1919] • Hine: Genus Erax 135 



pygium Slack with white hair. See Figure o3. Female, abdomen 

 with each segment marked with black dorsally, sides and posterior 

 margin of each segment white pollinose, oviduct somewhat longer than 

 the last three abdominal segments. 



Specimens from Montana, Wyoming and Colorado. 



There is some doubt as to the proper identification of 

 costalis, but the information available indicates that this 

 species is the one for which Williston used the name in his key, 

 Trans. Am. Ent. Soc, XII, 64. No description was ever wtriten, 

 and Aldrich did not give it in his catalogue. 



The tuberculatus Group. 



The males of this group are at once known by the presence of a 

 tooth-like prominence on the venter of each of abdominal segments 

 four, five and six, and costa entirely normal. Branching of the third vein 

 distinctly beyond the base of the second posterior cell. The species 

 are slender and of rather small size. 



1. Hypopygium and ventral tooth-like process of the abdomen red, 



spiniventris n. sp. 

 Hypopygium and ventral tooth-like processes black 2 



2. Ventral tooth-like processes of the abdomen all arnte at apex, 



tuberculatus Cociuillett 

 First two ventral tooth-like processes knobbed at the apex. . productus n. sp. 



Erax tuberculatus Coquillett. 



Total length 15 to 17 millimeters. Body gray pollinose and white 

 hairy, ocellar bristles and some bristles in lower part of mystax black, 

 palpi black hairy; femora, apices of tibia and tarsi black, tibia otherwise 

 red. Male with venter of abdominal segments four, five and six each 

 with an acute, black, tooth-like process produced downward. The 

 presence of these ventral spines will put the male into its group at once, 

 wings hyaline, branching of the third vein distinctly beyond the base 

 of the second posterior cell, stump usually shorter than the basal section. 



There is no very good way to characterize the females, but the small 

 size and the forking of the third vein distinctly beyond the base of the 

 second posterior cell are suggestive of the group. The oviduct is only 

 slightly longer than abdominal segments six and seven in tuberculatus, 

 but longer in other species of its group. 



The type is in the United' States National Museum. Other 

 specimens from Davis Mountains, Texas (F. M. Gaige), and 

 from West Fork, Texas (J. E. Scherer), taken in June. 



Erax spiniventris n. sp. 



Male. Total length 12 millimeters. Yestiture of the body largely 

 white, ocellar bristles black, bristles of the legs largely white, but now 

 and then a black one is intermixed; tibiae, except the extreme apex of 



