^26 INSECTA. 



it being only the females which bite.] The alulets generally cover the halteres ; the abdomen is de- 

 pressed and triangular ; the tarsi have three pulvilli. 



These insects appear towards the end of spring, and are very common in woods and pastures, flying 

 with a buzzing noise. They even attack man, to suck his blood ; and cattle in some parts are some- 

 times nearly covered with blood from the continued attacks of these insects. That of which Bruce 

 has spoken in his Travels, under the name of Tsaltsalyia, and of which even the lion is afraid, is prob- 

 ably a species of this genus. 



Pangonia, Latr (Tanyglossa, Meig.), has the proboscis much longer than the head, slender, scaly, generally 

 pointed at tip, and with very short psilpi : the last joint of the antennae is divided into eight rings. The species 

 are only found in hot climates, and subsist on the honey of flowers. 



The rest have the proboscis shorter, or scarcely longer than the head ; membranous ; terminated by two large 

 lips, and with the palpi at least equal to half the length of the proboscis ; the last joint of the antennae is divided 

 into five or four rings. 



Tabanus proper, has the antennae scarcely longer than the head ; the last joint is rather crescent-shaped, and 

 divided into five rings, the first largest, with a tooth above. T. bovinus, De Geer, the Large Gad-fly, the larva of 

 which lives in the ground : it is long and cylindric, narrowed towards the head, which is armed with two hooks ; 

 the pupa is naked, nearly cylindric, with two tubercles in front ; the segments of the abdomen ciliated ; and six 

 points at its posterior extremity. 



Tabanus maroccamit, Fabr., according to Desfontaines, attacks camels, which are sometimes covered with them. 



The others have the antennae evidently longer than the head, and terminated by a joint of an elongate-conic form, 

 or nearly cylindric ; and generally only with four annuli. The ocelli are wanting in many. 



Silvius, Meig., has three ocelli, and the first joint of the antennae is longer than the following, and cylindric. 



Chrysops, possesses three opelli, but the two basal joints of the antennae are nearly of equal length. C. aecutiens, 

 Fabr., a common species, which greatly torments horses. 



Iliematopota, Meig., wants ocelli, and the basal joint of the antennae is thick, and nearly oval in the males. 



Hematoma, Meig. (Heptaioma, previously), has the antennae larger than the preceding, and cylindric, with the last 

 joint very long ; ocelli wanting. 



THE FOURTH FAMILY OF THE DIPTERA,— 



The Notacantha, — 



Has, like the last, the third and last joint of the antennae transversely annulated, or composed of five 

 distinct joints (Chiromyza) ; the sucker is formed of only four pieces ; the proboscis, of which the stem 

 is very short, is nearly withdrawn into the oral cavity : the membranous consistence of this organ, and 

 its reflexed lips ; its clubbed palpi, also reflexed ; the arrangement of the wings, which are mostly crossed 

 over each other ; the oval or orbicular form of the abdomen ; and the scutellum often armed with 

 points, distinguish the Notacantha from the Tabanides. But few of their larvae have been observed : 

 those hitherto observed, and which have been described by Swammerdam, Reaumur, and Rosel, are 

 aquatic (see below), and approach those of the Athericera by their soft head of a variable form, [?] and 

 by their habit of changing to pupae beneath their own skins ; but they preserve their former size and 

 form, which is not the case with the Athericera. The larvae of other Notacantha (Xylophagus), live in 

 the rotten and moist parts of trees. 



We divide the Notacantha into three principal sections, [Mydasii, Decatoma, and Stratiomydes]. 



The first, Mydasii, have no teeth or spines on the scutellum ; the body is oblong, with the abdomen 

 long, triangular, and conical; the wings are extended; the antennae, which constitute the chief 

 character, are composed either of five distinct joints, two of which form in some a club, and in others 

 the extremity of a cylindrical stem ; or of three joints, the last of which is largest, nearly cylindrical, 

 gradually pointed, and divided into three annuli ; so that these organs are always divided into five. 

 If we except Mydas, in which we have the rudiments of a style, neither the latter nor the seta exists 

 in any of these Notacanthae ; probably the two terminal joints represent them. 



Some have the antennae much longer than the head, 5-jointed, terminated in an elongate mass formed of the 



last two joints, with a very short terminal seta; the hind thighs are strong, and toothed or spiny beneath. The 



tarsi have only two pulvilli. The posterior cells are closed before reaching the apex of the wing. These Diptera 



compose the genus 



Mydas,— 

 Which is divisible into two subgenera. 



Cephalocera, Latr., has the proboscis long, and advanced. 



Mydas proper, has it short, and terminated by two large iips. 



Others have the antennae scarcely longer than the head, and cylindric ; the tarsi have three pulvilli, and the 

 posterior cells extend to the hind margins of the wings. 



