OF MAXILLUL.E IN THE ORDERS OF INSECTS. 



441 



Iiemevobius. — The appearance of the month-floor of an adult specimen of 

 Hemerobius sp. as seen from the dorsal surface is illustrated in text-fig. 9 

 (p. 442). It is seen that from the membranous hypopharynx (A) arise a pair 

 of lateral lobes (m.), the surface of which, like that of the hypopharynx, is 

 covered with minute setse (not shown in the figure). These lobes are, 

 according to my interpretation, maxiilulse which have assumed a somewhat 

 ventro-lateral position with regard to the hypopharynx. 



Later a fresh specimen of Clirysopa flava was examined. The labium and 

 hypopharynx resembled those of Hemerobius in general characters and also 

 in their relative position. Prominent lateral plates were present at the sides 

 of the hypopharynx, entirely clothed with long fine setse. They could be 

 reflected outwards to a considerable extent. 



It was hoped that investigation of the hypopharynx in larval and adult 

 Neuroptera might throw light on the origin of the condition in which it 



Text-fig. 8. 



-OS 



Sialis lutuaria. Labium and hypopharynx viewed from before. /I. Hypopharynx. /. Ligula 

 of labium, m. Maxillular lobe. p. Palp. o.s. Opening of salivary duct. s. Setae 

 bordering- maxillula ventrally. 



occurs in some of the mandibulate forms of Endopterygota. Now, let us 

 suppose that the labium of Forficula were so reduced as to bear but a single 

 median endite, and its sides fused with those of the tongue. The resulting 

 structure would bear a distinct resemblance in constitution and appearance 

 to the condition in Raphidia. These considerations suggest that in the latter 

 such reduction and fusion have taken place. The maxiilulse in Forficula 

 would, moreover, occupy precisely the same position with regard to hypo- 

 pharynx and labium as do the lobes (m.) in Raphidia. It is therefore 

 probable that these latter are wholly or partially the persistent maxiilulse. 

 In a later part of the present paper I have attempted to demonstrate a 



LINK. JOURN. — ZOOLOGY, VOL. XXXIV. 33 



