222 
Transactions of the Royal Society of 'South Africa. 
no appearance of segmentation or of head. Covered on the dorsal region 
with a network of broken white lines made up of peculiar setae with 
flattened, stellate heads, with a narrow line, bare of setae, running longi- 
tudinally along the back ; the border between the dorsal and ventral 
regions is armed with a narrow, inconspicuous fringe of peculiar, membranous 
hairs ; there is also a white, beaded line of setae running round this border. 
The terminal stigmata are very prominent, almost contiguous, and situated 
on a prominence having a conspicuous white periphery, the stigmata sur- 
rounded by brown, strongly cliitinised lips. 
Piqmrium. — Exactly the same as the larva, except for the presence of 
two prominent cliitinous horns about a third of a millimetre in length, 
deep brown in colour, and situated at the anterior end of the dorsal region. 
Dehiscence occurs transversely along a line just posterior to these horns, 
the puparial skin bursting irregularly into three triangular pieces, the adult 
emerging through the opening thus made ; there is no ptilinum. 
Adult. — Length of body 8 mm. Head wider than thorax, black, frons 
covered with conspicuous silvery pubescence, ocellar region bare ; eyes fringed 
with silvery hairs ; 1st joint of antennae longer than third, brown, 2nd joint 
short, terminal joint stout and blackish brown in colour. Thorax black, 
punctate, quadrate, thinly covered with a fine, greyish pubescence ; a con- 
spicuous band of golden-yellow hairs, broken in the middle, runs transversely 
across the thorax along the suture ; a much less conspicuous band runs along 
the anterior border of the scutellum. Scutellum black, shining, rounded,, 
armed with two small, curved, black spines. First segment of abdomen 
small, same width as the scutellum, black ; 2nd elongated, constricted in the 
middle, black, with a narrow, yellow streak on each side, leaving in the centre 
a black median line broadening out anteriorly and posteriorly ; remainder of 
abdomen black, with a greenish sheen in strong light, covered thinly with a 
fine, greyish pubescence ; 4th segment longer than 3rd or 5th ; two con- 
spicuous bands of golden yellow hairs run along the hind border of the 3rd 
and of the 4th segments. Four front legs testaceous, with fuscous femora ; 
hind femora black, proximal half of hind tibiae white, distal half blackish 
brown, tarsi testaceous. Wings hyaline, except for slight infuscations 
along some of the veins, middle cross-vein situated on the basal third of the 
discal cell, third longitudinal vein provided with the usual peculiar stump 
in the subapical cell. 
One specimen, a female, lodged in the S.A. Museum, Cape Town. 
EXPLANATION OF PLATE XIII. 
Fia. 
a. Microdon illucens, Bezzi. $ x 10. 
b. Microdon illucens, Bezzi. Larva. x 8. 
c. Microdon illucens, Bezzi. Puparium, showing- lines of dehiscence {x). x 8. 
