580 Dr. D. Keilin on the 



with 4 pairs of sensory circular papillae, followed by 3 pairs 

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

 pair of short conical papillse, one single median transparent 

 papilla^ 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 maxiUcB (PI. XIX. fig. 3) are very flattened and reduced 

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

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

 drical papillae, followed by (d) an ordinary circular papillse 

 and {e) a protrusihle vesicle bearing 3 to 4 small papillae. 



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

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

 which are clearly visil)le from the side. 



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

 ending in 17 to 19 teeth. 



Text-f]ff. 3. 



Basyheka ohscura : labium of thje larva, seen veutrally. 



The hyjjopharynx is very mcII seen by transmitted light 

 as a very dark transverse chitinous sclerite occupying the 

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

 structure is much more complicated than was described by 

 Goetghebuer (1914, p. 183, pi. ii. fig. 2) in a closely-allied 

 species of Dasyheha. It does not form one solid chitinous 

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

 following four independent sclerites (PI. XIX. figs. Qh7^ : — 

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

 strongly chitinized and showing two ventral projections : one 

 near the base of the triangle and another near the 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 setse directed backwards. The surface of this sclerite 

 when examined ventrally shows four successive zones : 

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

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

 a more roughly granulated zone. 



(2) The dorsal sclerite (f/.) is very strongly chitinized and 

 of almost quadrangular shape ; it also bears posteriorly a 



