488 INSECTA. 



These Insects begin to appear towards the close of spring, are very com- 

 mon in. the woods and pastures, and produce a humming noise when on the 

 wing. They even pursue Man in order to suck liis blood. Beasts of bur- 

 den, having no means of repulsing them, are most exposed to their attacks, 

 and are sometimes seen covered with blood from the wounds they inflict. 

 The Insect mentioned by Bruce, under the name of Tsaltsalya, which is 

 dreaded even by the Lion, may possibly belong to this genus. 



T. bovinus, L. An inch long; body brown above, grey beneath; eyes 

 green; tibix yellow; transverse lines and triangular spots of pale yellow on 

 the abdomen; wings transparent, with russet-brown nervui-es. 



The larva lives in the ground. It is elongated, cylindrical, and attenua- 

 ted towards the head, which is armed with two hooks. The nymph is 

 naked, and ascends to the surface of the soil when about to divest itself of 

 its skin, in order to assume the form of a Tabanus, and protrudes the half 

 of its body above it. 



FAMILY IV. 



NOTACANTHA.(l) 



The fourth family of the Diptera, as well as the preceding one, 

 presents antennae of which the third and last joint is divided trans- 

 versely in the manner of a ring, or which are even composed of five 

 very distinct joints; but the sucker is formed of only four pieces, 

 and the proboscis, the stem of which is usually very short, is almost 

 entirely retracted within the oral cavity. The membranous nature 

 of that organ and its turned up lips, its similarly raised and clavate 

 palpi, the relative disposition of the wings which are usually crossed, 

 the form of the abdomen which is rather oval or orbicular than tri- 

 angular, and finally the scutellum which is frequently armed with 

 teeth or spines, also distinguish the Notacantha from the Tabanides. 



But few of their larvae have been observed. Such as have been 

 discovered are described and figured by Swammerdam, Reaumer 

 and Roesel, are aquatic, and approximate to those of the Athericera 

 in their soft head, varying in form, and in their habit of becoming 

 pupae under their own skin; but they retain their primitive form and 

 proportions, thus differing from those of the latter. 



Other larvae of the Notacantha — Xylophagus — live in the carious 

 and diseased parts of trees. 



1) Spiny-backed. 



