AN INTERESTING OCEANIC SPECIES OF 
CERIOIDES (DIPTERA; SYRPHIDiE) 1 
By F. M. Hull 
University of Mississippi 
I am indebted to Dr. Joseph Bequaert, Curator of In- 
sects at the Museum of Comparative Zoology, for calling 
my attention to the following interesting species of 
Cerioides. 
Cerioides (Tenthredomyia) williamsi n. sp. 
Related to oceanica Hull; differing in the pattern of 
the yellow markings. 
Male. Length about 16 mm., including the down- 
flexed abdomen, and including antennae (2 mm.). Head: 
vertex and front shining black and almost bare. Upon 
the front there is on either side a sunken, hemicircular, 
opaque black pubescent, eye marginal area ; at the upper 
end of this area there is a small patch of brownish-white 
pubescence. The face is dully shining black, with a 
sharp, wide, pale, yellow stripe on either side ; this stripe 
margins the eyes on the upper half to the upper limits of 
the antennal pedicel, and below the stripe narrows as it 
is directed along the anterior, black cheek margins to 
the epistoma which it just fails to reach. The antennae 
are entirely velvet black; the first segment is barely 
longer than the third, the third a trifle longer than the 
second; the pedicel is about as long as the second seg- 
ment. Thorax: brilliant shining black with large, bright, 
pale yellow spots. These spots consist of the humeri, a 
spot on each side at the lateral end of the transverse 
suture (notopleural), a vertical spot covering most of the 
mesopleura, and all the scutellum except for a black, 
round, middle portion, which does not quite reach its 
posterior margin. Abdomen: broad at base, but little 
constricted, everywhere shining black, and with faint 
blue-purple luster apically. The narrow posterior mar- 
1 Published by a grant from the Museum of Comparative Zoology at 
Harvard College. 
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