440 



MISS A. M. EVANS ON THE STRUCTURE AND OCCURRENCE 



In the larvre of Sialis and Chrysopa the hypopharynx was not found to 

 bear any distinct indications of maxillulse. 



Sialis. — The labium of the adult Sialis is described by Westwood 

 (46. vol. ii. p. 50). He states that the true labium, "ligula," does not 

 extend beyond the palpi but is " internally dilated.-" Packard (36. p. 73) 

 describes the lingua of Sialis. It is, he says, short rounded and little 

 developed. He notes the presence of sensory hairs at the edge similar to 

 those borne by threads of the maxillary and labial palpi. 



Text-fig. 7. 



Saphidia sp. Tongue, dorsal aspect. X 90. a.m. Cliitinous bar arising from mentimi. 

 h. Hypopharynx. 1. Ligula. m. Maxillula, p. Labial palp. 



In text-fig. 8 (p. 441) this structure together with the hypopharynx (h.) 

 is shown as viewed from before. (/.) is the anterior border of the labium 

 (ligula). At each side the labium is connected internally to the palp (p.), 

 -with a large rounded lobe bearing small fine setse and at the end a row of 

 long stiff hairs : apparently those referred to bj r Packard. Viewed from 

 the dorsal surface these lobes present much the same appearance as the 

 similarly located structures in Rapliidia. They may therefore be maxillulse. 

 This view as to their nature is based partly on the fact that here as in 

 Raphidia their texture resembles that of the mouth- floor and differs from 

 that of the " ligula." 



