DIASTATA. 235 



large black spot in front of the tip, with a black spot on each of the 

 transverse veins, and with a black dot on the fore border near the base ; 

 discal transverse vein nearly upright, parted by more than twice its 

 length from the prsebrachial transverse, and by less than its lengt' 

 from the border. Abdomen black. Legs tawny. 



Common. (E. S. I.) 



The following additional species of Opomyza have been recorded 

 as British : 



1. marginella, Fal. 4. tremula, Hal. 



2. sabulosa, Hal. 5. asteia, Hal. 



3. cinerella, Hal. 6. grisea, Fal. 



Genus III. DIASTATA. 



DIASTATA, Meig. Zw. vi. 94 (1830) ; Mcq. ; Zett. Geomyza p., Fal. 



Corpus parvum, sublineare, sat angustum. Caput et thorax convexa, 

 subsetosa. Caput transversum, breve, thoracis latitudine. Antenna 

 facie vix breviores ; articulus tertius sublinearis ; arista parce plu- 

 mosa. Thorax ellipticus. Alse sat angustee. Abdomen thorace 

 paullo longius. Pedes mediocres. 



Body nearly linear, rather narrow. Head and thorax convex, with 

 a few bristles. Head transverse, short, as broad as the thorax. An- 

 tenna nearly as long as the face ; first and second joints very short ; 

 third joint nearly linear ; fourth and fifth obsolete ; sixth long, slender, 

 setiform, thinly plumose on each side. Thorax elliptical. Scutellum 

 small, obconical. Wings moderately long and narrow ; costal vein end- 

 ing on the hind border near the tip of the wing ; subcostal ending at a 

 little beyond one-fourth of the length ; radial ending at some little dis- 

 tance in front of the tip ; cubital ending at the tip ; praBbrachial ending 

 at the tip of the costal ; discal transverse parted by thrice its length 

 from the prsebrachial transverse, and by more than its length from the 

 border. Abdomen with six or seven segments, longer and a little nar- 

 rower than the thorax. Legs of moderate length and thickness. 



The Diastata inhabit woods. 

 a. Thorax not striped. Species 1. 

 a a. Thorax with three stripes. Species 2. 



1. obscurella, Fal. Geomyz. 4. 6 (1820) ; Meig. ; Mcq. ; Zett. 

 Picea, capite antennisque luteis, alis subcinereis basi fuscis, halteribus 

 testaceis, pedibus fulvis. Long. If ; alar. 3 lin. 



Piceous. Head luteous, whitish in front and beneath. Proboscis 

 and palpi yellow. Antennae luteous. Wings greyish, brown in front 

 near the base ; veins black. Halteres pale testaceous. Legs tawny. 



Not common ; frequents damp and shady woods. (E.) 



