2 



DIPTÜKA 



was Bhpharocera [^sihenia) fasciata Westwood, described in 1842 from a specimen taken in Albania on 

 the Balkan peninsula. Macquait described the same species, in the Ann. Soc. Ent. Fr.. 1843, from a 

 female specimen taken by Mr. Arnaud in 1841. The other few European species were discovered slowly, 

 one at a time, as were also the few South and Central American species, and the single species recorded 

 from Ceylon. In i863 Osten-Sacken found the first North American species, Blepharocd'a tenuipes. Since 

 that time the additional North American species have been found also slowly and one at a time until 

 igoi, when four new species were discovered in one localit}- in California. There are known to-day 

 twenty species of these curious flies, well distributed over the world. There are certainly other species 

 to be found, but there are probably not many. The. flies are too conspicuous and characteristic long to 

 be overlooked in any locality visited b}^ collectors. However, their favorite haunts are rather removed 

 from the more usual collecting grounds of entomologists. Special search will have to be made in 

 mountain regions, where clear, swift streams run over clean rock beds, if the still unknown living species 

 of the family are Ui be discovered. 



Family Characters. — The flies are moderate-sized, elongate and bare, with long legs and 

 broad wings. These wings (pi. 2) contain no discal cell and have a peculiarly large and angular anal 

 lobe. In some species there is apparent a strong iridescence of the wing surfaces, although in others 

 these shifting colors are not so obvious. Alula, tegula and anti-tegula are absent or rudimentär}'. The 

 unique character is the presence of the « secondary venation », or the net of rather faint, fine crease-like 

 lines on the wings (pi. i, frg. 7; pi. 2. fig. 19). This net-like lining has nothing in common with the 

 primar}' or true venation, but is simply the result of the folding of the wings in the pupa. Because of the 

 curious habits of life (spoken of in the latter paragraph on the biolog}' of the insects) the wings must 

 necessarity be fully developed at the moment that the imago issues from the pupa. But that these fully 

 developed wings may be accomodated underneath the pupal cuticle it is necessary that they be strongly 

 and repeatedl}' folded. The lines of these foldings constitute the so-called « secondai'}- venation » charac- 

 teristic of the imaginai wings. The eyes are usually dichoptic in both sexes, but are occasionally 

 holyptic in one or both sexes. They are usually bi-sected by an unfaceted cross-band or line separating 

 each eye into two fields, an upper and lower one, the upper composed of larger and less pigmented 

 ommatidia (large and brown facets), the lower composed of smaller and more strongly pigmented 

 ommatidia (small black facets) (pi. i, figs, i, 2, 3, 4 and 12). In a few species the eyes are bi-sected only 

 in one sex. Three rather large ocelli are present. The antennae (pi. 2, figs. 16 and 17) are slender, with 

 from nine to fifteen segments clothed with a short pubescence. The mouth parts (pi. i, fig. i3) are 

 elongate, the females having in addition to labium and maxillae, slender flattened elongate saw-like 

 mandibles; the males are without these mandibles. Both sexes have a slender elongate labrum- 

 epipharynx, a similarly slender elongate hypopharynx, a pair of slender blade-like maxillar with 

 five-segmented palpi, and labium with slender elongate basal sclerite and a pair of free, fleshy, terminal 

 lobes without pseudo-tracheae and with no palpi. The thorax has a distinct, broadly interrupted, trans- 

 verse suture. The legs are moderately slender and comparatively long, the hind pair much longer than 

 the anterior ones, the front femora of the males curved in some species, the tibiae with or without spurs, 

 the ungues generally somewhat incrassate at the base, sometimes beset with stifi", minute bristles on the 

 outside; the empodia very small, almost rudimentary, and the pulvilli wanting. The forceps ol the 

 male (pi. 2, fig. i5) are somewhat like those in Limnobina, but are flatter, with various modifications; 

 the ovipositor of the females (pi. 2, fig. 14) is composed of two small, rather obtuse, lamellae. 



Biology and Habits. — The eggs and egg-laying of the Blepharoceridse are yet unknown. 

 However, from the circumstances of the larval life it is nearly certain that the eggs are deposited on 

 sprayed or otherwise wetted stones just above the water in swift, clear mountain streams, or on wetted 



