128 An^ials Entomological Society of America [Vol. XII, 



than thirty very well preserved specimens for study the lit- 

 erature has been consulted fully and the above synonymy 

 worked out. I have no doubt the males and females before me 

 are the sexes of the same species. They seem to combine with 

 characters mentioned by Fabricius, Macquart and Walker who, 

 as a usual thing, seem to have had each a single specimen in 

 hand. Thus the descriptions of stylatiis and invarius were taken 

 from females, while those of caiidex and haitensis were of males. 

 The name caudex, as Walker indi'cates, was used because of the 

 "very large" genitalia. Macquart's figure of the wing of 

 haitensis shows the distinctly dilated costal border which is 

 shown in the males before me. The large size Walker gives for 

 invarious, together with other characters, is good proof of its 

 synonymy with stylatiis. These statements are emphasized 

 when it is pointed out that among no less than eight West 

 Indian species this is the only one that combines the dilated 

 costa and large male genitalia, while only one other has a 

 slightly dilated costa and one a somewhat enlarged hypopygium. 

 Most likely Van der Wulp was in error when he reported 

 stylatiis from Wisconsin. The descriptions given by all the 

 author's mentioned in this connection are more or less deficient 

 and one could easily apply them to several species of the genus. 



Erax rufitibia Macquart. 



Total length IS millimeters. Rather dark species, thorax and 

 abdomen largely gray pollinose. Mystax black with a few white hairs 

 intermixed, beard white, palpi black haired, hairs and bristles of the 

 thorax all black; wing slightly fumose, no costal dilation in the male, 

 anterior branch of the third vein with a stump which is about equal in 

 length to the basal section. Femora black, tibias and tarsi almost 

 wholly red. Sixth and seventh abdominal segments silvery in the male, 

 genitalia of male short, somewhat tumid. Figure 30. 



Females agrees with the male except in sexual characteristics. 



From Bahamas and Cuba. 



Erax portoricensis n. sp. 



Total length 20 millimeters. Mystax, hairs of the palpi and beard 

 white, an occasional black hair in the mystax, dorsum of the thorax 

 largely rusty brown pollinose, wings pale brown, nearly hyaline, costal 

 margin not dilated, stump of the anterior branch of the third vein 

 equal in length to the basal section, femora and tips of tibiae black, 

 basal three-fourths of tibiae yellowish brown, tarsi dark reddish brown, 

 nearly black, with abundance of black bristles. Abdomen darker 



