1876] 207 



space wide. Thorax with three posterior dorsal briwtlcs. Posterior 

 tibiae o£ ^ bare. J^cngth, 3 lines. 



Sead: width of frontal space in S rather more than a fourth of the breadth of the 

 head. Central stripe black, and rather more than double the width of the whitish-coloured 

 interval between it and the eye on each side. 



Thorax striped in the usual manner, and armed with five lar^e dorsal bristles, two in 

 front and three behind the transverse suture, as in S. melanura (figure 2). 



Abdomen without central spines upon the edge of the second segment. Dorsum marked 

 by a longitudinal central stripe, formed by three elongated triangular black spots. Sides tes- 

 Bellated with irregularly-shaped black spots. First anal segment of <J pale grey, second 

 light red. Terminal segments of ? reddish-brown. Wings without costal spine. Legs 

 with posterior tibiiB of <J smooth. 



E-are. Two ^ and one ? of this species are in Mr. Verrall's col- 

 lection, all captured at Penzance. 



20.' HiEMOEEHOA, Meig., Zett., Schin., Eond. 

 vulnerata, Schin. 

 Yellowish or whitish-grey, striped and tessellated with black. 

 Frontal space narrow. Second and fourth longitudinal veins of wings 

 Betigerous. Second abdominal segment with two central spines. First 

 anal segment of ^ black, with a grey spot, second red. 



Length, 3 — 4 lines. 



Sead : frontal space of ^ not more than one-sixth of the width of the head in breadth, 

 and entirely black. In ? the space is nearly twice as wide. 



Thorax marked and armed as in S. hcematodes. 



Abdomen with second segment armed with central dorsal spines upon its posterior edge. 

 Colour pale grey, tessellated with three longitudinal rows of black irregularly-shaped confluent 

 spots. First anal segment of tJ black, marked with a grey patch, second dull red. Termi- 

 nal segment of 9 pale yellowish-red. Wings with base tinged with brown. Costal spine 

 small, but generally distinct. Second as well as fourth longitudinal veins setigerous. Fifth 

 longitudinal vein bent at a right or obtuse angle. Legs with the posterior tibiae of <J either 

 bare, or ciliated with a few longish hairs when it constitutes the species vulnerata of 

 Schiuer. 



Not rare. 



In conclusion, I may remark, that while investigating the minute 

 differences w^hich separate the species of this genus from each other, 

 the question will arise, are these differences in structure sufficient, in 

 many cases, to separate these flies from each other as specifically dis- 

 tinct, or are they only varieties of one or two types ? I can only say 

 in answer, that the characters upon which the foregoing species are 

 founded, will be found to be mostly constant and fixed, and that one 

 distinctive point of difference is almost always accompanied by some 

 other. The only species about which I have any doubt, is No. 4, 



