1921] 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
51. 
52. 
53. 
54, 
59. 
56. 
57. 
58. 
59. 
69A. 
69B. 
70. 
&& 
72. 
73. 
74, 
75. 
76. 
Metcalf: Genitalia of Male Syrphide Zit 
Didea fasciata fuscipes, caudo-distal view of genitalia (*204). a, central 
lobe of trituberculate ejaculatory hood; 6b, earlike tuberosities of 
ejaculatory hood; cc, the overhanging flaps of the collar-like, 
chitinous box; d, the opening of the ejaculatory duct or ejaculatory 
process. 
Syrphus arcuatus; ventro-lateral view of genitalia (*210). 6, spurs at 
cephalic ends of collar-like chitinous box. 
Syrphus xanthostomus; lateral view of genitalia (*201). 6, spurs at 
cephalic endsxof collar-like chitinous box; c, apical tongue of 
sustentacular apodome. 
Syrphus knabt; disto-ventral view of genitalia (*205). 6 and c, as in 
Figure 53; a, the cephalic keel of sustentacular apodome. 
The same, in lateral view. Captions as in Fig. 54. 
Syrphus amalopis; lateral view of genitalia (*209). a, erect chitinous 
box. 
Xanthogramma tenuis Osburn (=Syrphus oronoensis Mtclf.) disto- 
lateral view of genitalia (*208). 
Chrysotoxum derivatum; caudo-distal view of genitalia (*201). 
Chrysotoxum pubescens; caudo-distal view of genitalia (*202). 
PLATE XIV. 
Sphegina lobata; dorsal view of preabdomen, the genital appendages seen 
in their cephalic aspect. The course of the left longitudinal tracheal 
trunk is shown from spiracle 5 to spiracle 8. 
Sphegina lobata; ventral view of preabdomen, the genital appendages 
seen from their caudal aspect (*18). a, ejaculatory hood; 6, apex 
of ejaculatory process; ¢, superior lobes; d, slightly thickened, 
apical rim of penis-sheath; e, chitinous box; f, caudal ramus of right 
style; s, point of fusion of ejaculatory process to ejaculatory hood; 
t, tongue-like caudal projection from between the bases of the inter- 
nal lobes. 
The same, genitalia from the right side. Captions as in Figure 69, 
except e, the internal lobes arising from the chitinous box; v, angle of 
sustentacular apodome, beyond which it widens, in cephalic aspect. 
Sphegina sp.; dorsal view of terminal segments of the postabdomen, 
showing the caudal aspect of the appendages (*222). a, the cephalic 
ramus of the right style. 
The same, genitalia from the left side. aa, cephalic rami of the styles, 
offset mesad from the base of the caudal ramus as shown to the right 
of the letter c; bb, the lever-like arms of the tenth sternite, which 
operate between penis rim and apices of cephalic rami of the styles; 
e, basal swelling of the cephalic face of the penis sheath. 
Sphegina petiolata; ventral view of preabdomen, the genital appendages 
shown from their caudal and distal sides, (*17 and 170). a, 
an anomalous, caudal lobe of the penis-sheath; c, the acute, cephalo- 
distal angle of the superior lobe; 0, the membranous lobe projecting 
from under the fifth sternite. 
The same, in disto-lateral view. s, caudo-internal lobe of right side, 
seen through the lateral wing of the penis-sheath; k, chitinous arm 
reinforcing the bonnet of the ejaculatory hood; 0, caudo-distal angles 
of superior lobes. Other captions as in Figure 73. 
Ventro-cephalic view of the same. 0, rudimentary inferior lobes?; 
d, the termination of the ejaculatory duct; f, the open cephalic face of 
the ejaculatory hood; s, transverse septum between cephalic face of 
ejaculatory hood and opening of ejaculatory duct; m, cephalic ray of 
sustentacular apodome; m, median or principal ray of sustentacular 
apodeme; x, a reinforced line across the cephalic face of the penis- 
sheath. (other captious as in Fig. 73). 
Sphegina rufiventris; cephalo-lateral view of genitalia (*4, 5, 7); a, the 
cephalic emargination of the penis-sheath; c, bonnet-like hood over- 
hanging the ejaculatory process. 
