946 REPORT OF THE HARVARD AFRICAN EXPEDITION 
cis is longer and more slender than usual, with long and rather narrow, chiti- 
nized labella, which, at any rate in the female, are nearly as long as the remainder 
of the labium. It is doubtful whether this proboscis is fit for biting and sucking 
blood. According to Grimberg’s description and figures, the third antennal 
segment shows four divisions, three of them belonging to the style. As a matter 
of fact, in all three specimens of 7’. akwa before me (one female and two males), 
only three divisions can be made out, two of them forming the style; and Sur- 
couf observed the same condition in his specimens. The antennae are inserted 
on a raised subeallus, separated by a depression from the much swollen face. 
The three ocelli are quite well developed. This latter character, however, is not 
unique in the Tabaninae, as Surcouf implies, for the North American genus 
Merycomyia Hine (a very valid genus overlooked or not recognized by both 
Surcouf and Enderlein) has the ocelli equally well developed. 
I fail to see any close relationship between Thaumastocera and the South Ameri- 
can genus Stibasoma Schiner, notwithstanding the toothed third antennal seg- 
ment of both genera (which, moreover, is also found in Acanthocera). Stibasoma 
lacks the ocelli entirely and has five distinct divisions in the third antennal seg- 
ment. 
I can recognize but two species of Thaumastocera: T. akwa Grinberg and 
T. nigripennis (Enderlein). 
Thaumastocera akwa Griinberg 
Thaumastocera akwa Grinberg, 1906, Zool. Anzeiger, XXX, p. 356, figs. 7, 8, and 9 ( 2; Johann- 
Albrechtshéhe and Lolodorf, Cameroon). Surcouf, 1921, ‘Gen. Insect., Tabanidae,’ p. 163, 
Pl. V, fig. 1a-b (9). 
Thaumastocera vittata Surcouf, 1923, Ann. Soc. Ent. France, XCI, 3, (1922), p. 241 (#; Ivory 
Coast). 
BELGIAN Congo. — Malela, in the estuary of the Congo River, one female, 
September 10, 1913. Stanleyville, one female and one male, as prey of Bembix 
bequaerti Arnold var. dira Arnold, March 1915 (H. Lang and J. P. Chapin). 
This species is West African, being known from Sierra Leone, the Ivory Coast, 
the Gold Coast, Southern Nigeria, Cameroon, Spanish Guinea, and the French 
and Belgian Congo. 
The pair from Stanleyville agree well with Griinberg’s original description 
of both sexes. The female is very fresh and shows the first two dorsal segments 
of the abdomen and the anterior half of the third broadly covered on the sides 
with grayish white pruinosity; the hind margin of the first segment bears in the 
middle a minute, pale brownish spot. The insect is otherwise coal black with 
black pilosity; the thorax with dark brown tomentum and two very narrow pale 
longitudinal lines, dilated at their tips, on the anterior half of the dorsum. The 
male shows no grayish pruinosity on the abdomen, but the median spot of pale 
brown on the first segment is more distinct and extends in a similar, larger, dif- 
fuse spot onto the base of the second; the last ventral segments are reddish 
brown; the thorax has two broad, yellowish brown, club-shaped stripes on the 
dorsum reaching from the anterior margin to the scutellum. 
