580 Dr. D. Keiliu on the 



\rith 4 pairs of sensory circular papillse, folloAved by 3 pairs 

 of ordinary sensory hairs, one pair of pectinate hairs, one 

 pair of short conical papillse, one single median transparent 

 papilhi, and, finally, a median soft protuberance covered with 

 short chitinous hairs. Viewed by transparency the labrum 

 shows also a strongly chitinized structure^ which serves for 

 the attachment of the labral muscles. 



The maxilla (PI. XIX. fig. 3) are very flattened and reduced 

 almost to a group of sensory organs, comprising («) a cir- 

 cular papilla, {b) a sensory hair, (c) a })it with 3 to 4 cylin- 

 drical papillae, followed by (d) an ordinary circular ])apill8e 

 and (e) a protrusit)le vesicle bearing 3 to 4 small papilla3. 



The mandibles (text-fig. 2, A, and PI. XIX. fig, ],m.) are 

 very strongly chitinized and j)rovided with 4 teeth, 3 of 

 which are clearly visible from the side. 



The labium (text-fig. 3) has the form of a chitinous plate 

 ending in 17 to 19 teeth. 



Text-fig. 3. 



h/V\^'^'^[. 



DasyheJea ohscura : labium of the larva, seen veutrally. 



The hypopharynx is very well seen by transmitted light 

 as a very dark transverse chitinous sclerite occuiiying the 

 central portion of the head capsule (PI. XIX. fig. 1, /(.). Its 

 structure is much more complicated than was described by 

 Goetgliebuer (1914, p. 182, i)l. ii. fig. 2) in a closely-allied 

 species of Dasyhelea. It does not form one solid chitinous 

 plate as represented by this author, but is composed of the 

 lollowing four independent sclerites (PI. XIX. figs. Q%i7) : — 

 (1) A ventral triangular plate (y.) with its lateral edges 

 strongly chitinized and showing two vential projections : one 

 near the base of the triangle and another near tlie anterior 

 angle of it, against the opening of the common duct {s.) of 

 the salivary glands. The basal portion of the ventral sclerite 

 forms a striated ridge (?•.) from which originate numerous 

 brown setae directed backwards. The surface of this sclerite 

 when examined ventrally shows four successive zones : 

 (a) clear zone which receives the salivary duct, (6) an uni- 

 formly pigmented zone, (c) finely granulated zone, and {d) 

 a more roughly granulated zone. 



(2) The dorsal sclerite {(I.) is very strongly chitinized and 

 o£ almost quadrangular shape ; it also bears posteriorly a 



