343 



FAMILY IV. 



NOTACANTHA. 



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 en- 

 tirely 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 trian- 

 gular, 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, Reaumur and 

 Rcesel, are aquatic, and approximate to those of the Athericera in 

 their softhead, varying in form, and in their habit of becoming pupre 

 under their own skin ; but they retain their primitive form and pro- 

 portions, thus differing from those of the latter. 



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

 and diseased parts of trees. 



We divide the Notacantha into three principal sections. 

 Those of the first — Mydasii, — Lat. — never have teeth or spines in 

 the scutellum. Their body is oblong, and the abdomen forms an 

 elongated and conical triangle. The wings are distant. Their an- 

 tennae, from which we draw their most distinguishing character, are 

 sometimes composed of five distinct joints, the two last of which form 

 a club in some, and the extremity of a cylindrical stem with a subu- 

 late termination in otliers, and sometimes of three joints, the last of 

 which is largest, almost cylindrical, tapers to a point, and is divided 

 into three annuli ; thus these organs are always divided into five. 

 With the exception of Mydas in which the vestige of a very small 

 stilet is perceptible, neither that appendage nor the seta which re- 

 places it can be found in any of the Notacantha of this section ; it is 

 possible that the two last joints may represent them. 



In some the antennae are much longer than the head, consist of five 

 joints, are terminated in an elongated club formed by the two last, 

 with an umbilicus at the end from which issues a very short seta. 



