32 Orthorrhapha brachycera. 



distinct, ring-like; it bears bristles or hairs above. Metathorax is 

 very small, and there is no metasternum developed, the part between 

 the first ventral segment and the hind coxæ being membranous. 

 There are as a rule dorsocentral and acrostichal bristles or hairs, 

 but they may be very variously developed, each kind present in 

 one or more rows, and of various length, most frequently short; 

 generally they are longest behind ; the acrostichal bristles may be quite 

 absent, and the thorax may be short and uniformly haired, without 

 observable bristles. There are as a rule humeral, posthumeral, some 

 notoplural, a supraalar and a postalar bristle; besides there may be 

 smaller bristles or hairs at the sides of the thoracic disc, There are 

 some (generally four) scutellar marginal bristles. Metapleura have 

 stronger or w^eaker bristles or hairs. Abdomen is generally somewhat 

 slender, cylindrical, consisting of eight segments; the first segment is 

 short, its tergite slightly broader than the following. The male 

 genitalia may show very different aspects, but seem however to be 

 of the same principal construction. For want of suitable material I 

 have only been able to examine their structure somewhat superficially. 

 As said above there are eight abdominal segments, the eighth seems 

 to form a complete ring which is not, as the other segments, divided 

 at the sides into a ventral and a dorsal half-ring by a lateral con- 

 necting membrane; the ring is often incised in the hind margin in 

 various ways, thus giving rise to projecting lamellar parts; the lower 

 part is often more or less protruding as an arched ventral plate. The 

 genitalia themselves seem to me to consist of two pairs of lamellæ, 

 the upper and the lower, forming two pairs of forceps; the upper 

 lamellæ are often very complicated and may, when dissected, show 

 branches inwards which are not visible when the organ is seen in 

 situ, or only the ends of them are seen, appearing as supernumerary 

 lamellæ; the upper lamellæ are often more or less connected with 

 each other and thus in reality consisting of only one piece. The 

 penis issnes from inwards just above the mentioned ventral plate 

 (eighth segment) and curves upwards between the lateral lamellæ; 

 it is thicker or thinner, often thread-like, and it may be simply 

 curved or more or less sinuous; at the ventral base of penis there 

 is (always?) a, generally small, sometimes cleft, ventral lamella, as a 

 rule only seen by dissection. In the female the abdomen is pointed, the 

 last segments being narrow, longer than broad; after the eighth seg- 

 ment follows a small ring terminating with two, somewhat long 

 styles. The legs are more or less slender, sometimes rather long; in 

 the males they sometimes show structural pecularities such as thickenings 

 or excisions of the hind femora and tibiæ, or they are provided with 



