82 MEDICAL ENTOMOLOGY 



the posterior border, and there divides into two. About the middle of 

 the wing there are two other long veins, which are not directly connected 

 with the wing base ; one of these arises from the first long vein and the 

 other independently. These are, therefore, the second, third and fourth 

 long veins. Behind them in the proximal part of the wing there are 

 two other long veins, the anterior one of which bifurcates, while the 

 other does not. These are the fifth and sixth veins. Those of the 

 veins which bifurcate produce forked cells named according to their 

 position. The anterior forked cell is enclosed by the two divisions of the 

 second long vein, and the first and second posterior forked cells by the 

 branches of the fourth and fifth veins respectively. The humeral and 

 axillary cross-veins are not present, and there is no discal cell. The 

 upper and middle cross-veins are nearly in line with one another, and 

 connect the third long vein with those in front of and behind it, a 

 short distance distal to its origin and about the middle of the wing. The 

 positions of the junction between the costa and the auxiliary vein, 

 the relative positions of the forked cells, and the point where the 

 fifth vein cuts the margin, are of importance in classification. 



The venation of Haematopota (Plate XVII, fig. 3) will serve as an 

 example of the application of Comstock and Needham's classification. 



The costa is conspicuous at the anterior margin, and 

 Haematopota *^ e subcosta arises in common with the vein behind and 



joins the costa after a very short course. The strongest 

 vein in the wing lies next behind, and is only separated from the costa by 

 a narrow interval; it gives off a branch internal to the middle of 

 the wing, and then divides into two ; the lower of the two divisions 

 so formed again divides, so that there are altogether four divisions 

 of the radial vein at the wing margin. Of these the second represents 

 the second and third divisions, the vein having failed to bifur- 

 cate as it does in the urotype. The bifurcation of the lowest division 

 into the fourth and fifth is peculiar, as the upper branch leaves the 

 lower at a wide angle, and then immediately turns outwards, so that 

 the two veins are parallel for a short distance instead of divergent. 

 At the point where the fourth vein turns outwards there is a pro- 

 jecting spur, which points inwards. Behind the main stem of the 

 radial vein there is another vein, which bifurcates about the middle 

 of the wing. The two branches so formed converge a little towards 

 one another about the middle of their length, and are connected by a cross- 

 vein, thus enclosing a discal cell ; the branch on the distal side bifurcates 

 at the level of the cross-vein, and there are thus three divisions of the 



