270 NATURAL HISTORY OF ARTHROPODS. 



to be mentioned, but appears to lack the other. One of these is based upon the 

 Halobates pieties, but has been described as a new genus, Stephaiiia. This sprightly 

 little insect lives in gay assemblages of many individuals upon the more quiet surfaces 

 of our eastern streams, from Massachusetts to Florida, occurring also in Cuba and near 

 Tamaulipas, Mexico. It is of a yellow color, with a black stripe on the head, which 

 is either interrupted or runs down to near the base of the rostrum ; the rostrum is 

 piceous, interrupted by yellow near the base ; on the prothorax two black lines along 

 the middle spread apart behind ; a similar line occupies each side, and is continued 

 unevenly back to the end of the mesothorax; on the latter a line runs down the 

 middle with a dot on each side ; and exterior to these the lateral, wider lines run 

 backward and curve inwardly until nearly meeting on the middle of the posterior 

 mai-gin. Most of the sutures on the abdomen, pectus, and flanks are black, and black 

 lines extend along the sides of all the legs. Many varieties occur in which the black 

 color invades more or less of the surface, particularly of the upper side, so that some 

 appear black, marked with a few yellow stripes and spots. 



If this genus is to be accepted, the characters jsresented by the thorax and wings 

 cannot be overlooked. In the unwinged state, although capable of laying eggs and 

 continuing the species, these insects fail to acquire their full plan of structure, and 

 there is consequently an arrest in the formation of the thorax. In this complete form 

 the wing-covers are elongate-obovate, smoke-brown ; the coriaceous part rather less 

 than half as long as the membrane, narrowly tapering towards the base, furnished 

 with three stout veins, the outer and inner of which run nearly parallel to the margin, 

 while the third extends along the middle, and ends in a small cell ; the boundary 

 between the two portions is made by a coarse transverse vein, and the base of the 

 costal margin is quite pubescent. The membrane has the outer and inner submarginal 

 veins of the corium continued through it to the tip, where the two unite in a loop ; 

 the middle one is continued to the very tip, in the form of a suture, and is paler than 

 the adjoining surface. The wings are also brown, opaque, much shorter and narrower 

 than the wing-covers, with three long veins reaching to the tip, and a basal one curv- 

 ing towards the hind margin. Here also the pronotum occuijies the whole width of 

 the dorsum, lacks the suture which divides it from the mesothorax, and the two itnited 

 are free, foiming a cap over the other segments of the mesothorax, and behind them 

 two transverse callosities, possibly the dorsal pieces of the metathorax, spread across 

 the base of the wide first abdominal segment. 



Thousands of these insects appear upon our streams of water every year, and I 

 have searched diligently to secure other winged specimens, but this single female, 

 which occurred to me while examining a group of them one very hot, but damp, 

 eighth of July, is the only one that has ever been found, and so leaves the history of 

 one sex still shrouded in mystery. Nor are we so well off in the genus Halobates, for 

 notwithstanding that they have been collected at various times of the year, in many 

 of the warm parts of the oceans, not a single winged specimen has been reported by 

 any scientific observer. 



It seems unlikely that wings could be of much use to creatures whose home is on 

 waters so distant froip the varying conditions of the mainland; but as we know that 

 some of these species, as, for example, the H. wuellerstorffii, approaches our southern 

 coasts, and from such places might have had its original distribution, it seems quite 

 likely that winged forms of this, if not all of the species, will yet repay the collector 

 who visits their places of refuge at the proper time of the year. 



