126 THK CANADIAN ENTOMOLOGIST. 



coat of felt, the color of which differs from that of the rest of the surface. 

 With only one exception ( ' Pyrgus Poggei), it is, in all the European Hes- 

 perians, either well developed or entirely absent ; in this respect it is a 

 good characteristic, but as a generic character,' is only to be taken cum 

 grarw satis, unless we would separate, without good reason, forms which 

 are naturally associated. 



I call that the discoidal stigma which Dr. Herrich-Schaeffer has 

 designated as " schuppenwulst " (a pad of scales), forming a peculiar 

 structure in the disk of the fore wings. The expression employed by 

 Herrich-Schaeffer would give a quite false idea of the nature of this 

 structure. The deep black streak of which it consists wholly or in part, 

 is neither a puffy elevation nor formed of scales, but is composed of a 

 dense felt-like substance of very fine, short, stiff and bristly fibres, as may 

 be seen by placing scrapings of it beneath the microscope. In its 

 simplest form {Thymelicus lineold) it is nothing but a slender black streak, 

 the surrounding part of the wing presenting no alteration in its normal 

 scaly covering. In case of increased extension of the streak, however, 

 the change affects also the surrounding area. The scales of the wing that 

 encircle it are raised and undergo various alterations, some of them 

 assuming the form of the antenna of a Diurnal butterfly. Still greater 

 changes take place in the structure of the whole area in the midst of 

 which this streak is placed in some American species (Pamphi/a 

 Huron Edw.). 



Less diversity appears in the situation and direction of the black 

 streak. It generally starts from the dorsal-vein,* either at the end of the 

 first third of its length, or a little before that point ; then it runs across 

 the first branch of the median-vein, where it is frequently contracted or 

 sometimes interrupted by raised scales, advancing in an oblique course 

 upward and outward to the origin of the second and third branches of the 

 median at the lower corner of the middle cell. Among the species known 

 to me, there occurs only in Pamphila mathias E., an essential deviation 

 in the situation and direction of the stigma. 



While the stigma furnishes good specific characters, it is of no generic 

 value, since in nearly related species it is at one time present and at 

 another absent. What appears to be of greater importance is the presence 

 or absence of a hair-tuft on the posterior tibiae. Of the Hesperidae here 



IGenerally known to American Entomologists as the submedian vein. — I.. I 



