SEPEDON. 145 



drops, first from the wide end towards the trunk, and then 

 in the contrary direction. It is conjectured that the neck 

 of this vessel is composed of two or more approximated 

 tubes, and that the blood is conveyed forward by the out- 

 ward ones, and backward by the intermediate one ; also that 

 there is a secondary heart, at the extremity next the thorax, 

 for the purpose of causing the reflux." 



BOKBORUS EQUINUS. 



These are very abundant everywhere in rank grass, and 

 near decaying vegetable matter, upon which the larvae feed. 

 They are small black flies, remarkable for their thick fleshy 

 labium, and a broad bellying sheath below, which should be 

 seen in profile. Antennas rather distant, short, and turn 

 outwards with a long slender arista ; the first joint so small 

 as to be scarcely perceptible, the second nearly as large 

 as the third, which is obliquely compressed and ciliated. 

 The legs are long, and fore-femora thickened; there is 

 a curious spine at the end of the hind tibia, and the tarsi 

 are short and broad. The wing, being very simply veined, 

 is an easy study ; the chief mark of this family being in 

 two small areolets near the base of the wing, close to the 

 hind border, which are called anal areolets, and in this 

 wing they are complete. The discal transverse vein is also 

 near the border; it joins the pmbrachial and pobrachial 

 together, the latter does not continue beyond it. The 

 radial and cubital are branches from one common vein at 

 the base. 



There is a full account of this species and its larvae in the 

 'Entomological Magazine' (vol. iii, p. 323). 



SEPEDON. 



A most beautiful specimen for the shape of the antennae 

 and the structure of the tongue. The wing closely resem- 

 bles that of Borborus, the same transverse veins and anal 

 areolets; but the antennae separate the genera entirely. 

 Instead of the short second joint in Borborus, that of Sepe- 

 don is very long and spiny, with a conical and convex third 

 joint, from which springs the three-jointed arista. 



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