1912.] 173 



offers the one exception to this condition of things, its anal organ issuing 

 in the usual way from underneath the saddle. Another feature 

 characteristic of the hypopygium in this genus is the very large size of 

 the ventral plate, as marked in citreiformis (where it is cleft almost to 

 the base) as in the other species. The saddle varies from quite tiny in 

 carinifrons and incrassata to large in femorata and mordellaria. Its 

 panels are always symmetrical, the left one never being fissured as 

 happens so often in Phora, and they are simple in outline, except in 

 citreiformis where they are produced behind into along narrow process 

 on each side as in the perennis group in Phora. 



Mr. Collin, who has drawn the figures in the plate, is of the 

 opinion that the part marked " a^ " in figures 1, 2, and 3, is the homo- 

 logue of the part marked " b " in figures 4 and 6, but the dissection of 

 several specimens has only served to confirm me in my views. 



EXPLANATION OF PLATE V. 



Fig. 1. Hypopygimn of Phora vitrea. Wood. 

 „ 2. „ „ „ abdominalis. Fall. 



„ 3. „ „ „ concinna, Meig. 



„ 4, ,, „ ,, urhana, Meig. 



„ 5. „ „ „ niaculata, Meig. 



COEEECTION. 



Vol. xlviii, page 98, line 24, for " errata " read " decipiens." 



SUPPLEMENTARY NOTES. 

 In view of the great size of Aphiochseta, and of the not altogether 

 satisfactory character on which have been grounded its two last sections 

 in the Table, it will, I think, be of material help to the student if I 

 give a second scheme choosing the costal fringe as the governing 

 character, and so enable him in doubtful cases to check the one by 

 the other. Moreover, the new scheme has an advantage over the old 

 one, inasmuch as the fringe seems to be quite uninfluenced by sex 

 and rarely, if ever, liable to variation, whereas the costa is subject at 

 times to both these disturbing influences. 



SECTION C. 

 Costal fringe short or very short. 

 In a few species — pygmxa, latifrovs, lata, tarsalis, lutescens, and collini, the 

 fringe might perhaps be considered only moderately short. 



1 (2). Cilia oil middle and hind tibias in two rows, one on either side the seam. 



...l\-2 mm. fasfiata- Fall. 



2 (1). Cilia on one side of the seam onlit 



