dl 24) 
XIV. Description of a peculiar unidentified Dipterous Larva 
possessing a number of enigmatic truncate Abdomi- 
nal Organs. By J. Bronté GATENBY, D.Phil.,D.Sc., 
Professor of Zoology, Trinity College, Dublin, 
Senior Demy, Magdalen College, Oxon. 
Prate XVIII. 
AmonG the material sent to Prof. E. B. Poulton by 
Mr. C. O. Farquharson was a small unidentified larva 
believed to be a Syrphid. Cursory examination of this 
larva showed that it possessed, on the ventral surface of 
the last third part of its body, a number of peculiar tubes 
arranged in two bunches set side by side. The ultimate 
region of the abdomen was found to bear a tracheal funnel, 
in somewhat the same manner as the larva of Hristalis 
fenax. In the unidentified larva, however, the funnel 
did not seem to be extrusible and extensile as in the rat- 
tailed Syrphid larvae. In Plate XVIII, fig. I, the larva is 
drawn to the centimetre scale given above. In front were 
two processes, short and with few joints, which were the 
antennae; the mouth-parts did not appear to be abnormal. 
From la to 6a in this figure were six pairs of processes 
surmounted by numbers of hooklets as in the Hristalis 
larva. Behind the last pair of leg-processes were found 
the truncate organs already mentioned (Plate XVIII, fig. I, 
Tu). In fig. II the organs on one side are drawn at a higher 
power. Each one was seen to have at its extremity a 
minute pore. Just behind the region of the truncate 
organs the body tapered sharply, but before passing on to 
the tracheal funnel it gave rise to two lateral, backwardly 
directed obtuse processes (PR in fig. I). 
The entire surface of the larva was covered with raised 
processes or rugosities, and the epidermis was markedly 
thick and pigmented towards the hind regions, somewhat 
like the Hristalis larva. Nothing of special interest was 
found in connection with the nervous or alimentary system, 
but the latter was of the complicated type found in many 
Dipterous larvae. The anus opened in the region of the 
truncate organs between the two bunches, so that the 
trunk-like tubes are really peri-anal. The two lateral 
tracheal tubes open behind at TT in fig. I. There are no 
TRANS. ENT. SOC. LOND. 1921.—PaARTS I], IV. (JAN. ’22) 
