38 



MU. K. M. SMITH ON CERTAIN SENSE-OHGANS 



have a difl'erent structure to tlioi^e of tlie other Diptera, as the 

 extei-nal passage is closed." I think Packard is mistaken here, 

 for my examination of the antenni?e of the Tipnlidfe revealed no 

 pits at all but only the " Trichoid " sensilli of 13erlese. 



Text-figure 1. 



Text-fiyure 2. 



Transverse sections through the middle cf the anteniue of an imdeterniined 

 Tipulid and of Paohi/rrJiina Jiistrio. X 980. 



Except where otherwise stated, all the sections are through the third joint 

 of the antenna;. 



Explanation of Lettering on the figures: — ^j?., aperture of pit: B., base of 

 hair ; C, cells ; Cfi., cliitin ; H., hairs ; N., nerve ; Nti., nuclei ; Sp., sensory 

 process or sensillus ; T., top of second joint of antenna. 



PsYCHODiD^ (Text-fig. 3). The form examined was Psychoda 

 albipennis Zett., determined by Rev. A. E. Eaton. 



In this insect the apparent sensory apparatus consists of a pair 

 of pseudopodia-like processes on opposite sides of each joint of 

 the flagellum. These processes are very large for the size of the 

 insect and are triradiate. They are exactly comparable to the 

 sensilli of Tipulidpe, consisting as they do of an outpushing of 

 very thin chitin, only in this case they are cai'ried to an enormous 

 length and are three-branched. There is also a very thick ring 

 of long hairs situated at the base of each joint. In text-fig. 3 only 

 their bases (B) are shown so that they should not block out the 

 triradiate processes. In the palps there is no special sensoiy 

 apparatus visible. 



Specialised processes or " chfet?e " of this type have been 

 described in several other Psychodidaj, In BrunetUa su2)erstes 

 Ann,, they are single, large, and spirally curved ; and processes 

 of this form are also present in several other species belonging to 

 more than one genus (see Brunetti, ' Fauna of British India,' 

 Dipt. Nematocera, 1912, pp. 198-9, 248, &c., and pi. 4). Eaton 

 also refers to chajtse of somewhat the same type in Telmatoscojnis 



