INTRODUCTION, 



2t 



valvi My purpose is, to give a review of those characters only, 

 which have been used in the classification, and to furnish some 

 explanations necessary for the better understanding of the present 



monograph. .,•«.! ^ 



The organs of the mouth of the Tip. brevzpalpi afford com- 

 paratively few characters for the classification. The prolongation 

 of the head in front, called the rostrum (compare Ilonograph,, 

 etc Vol I, p. xiii) is generally shorter here than in the 2. p. 

 longipalpi; it is considerably prolonged in tl- genera i^mm- 

 phidla, Toxorrhina, and Elephantomuia, and then be ai. the 

 palpi at its tip. The outer envelope of the rostrum has some- 

 times the shape of a short tube ripped open on the under sice ; 

 often, however, it is hardly tubular at all, but has rather the 

 appearance of a labrum, and is either short and stout, or long, 

 narrow, and linear (Geranomyia). Whenever I wanted to des g- 

 nate this outer envelope of the rostrum separately, as an inde- 

 pendent organ, I have called it epistoma. The proboscts consists 

 chiefly of the under lip, with its suctorial flabs ; it projects more 

 or less beyond the epistoma; the flabs are usually somewha 

 pubescent, linear in the Limnohina, more stout and fleshy m the 

 LimnopJuUna, Amalopina, etc. ; (in Geranonujia the under lip s 

 very much prolonged and bilobed, the lobes being likewise long 

 and linear) The palpi incurved backwards, when at rest, are 

 four-jointed; a fifth joint, sometimes perceptible at tbeir basis, 

 probably represents a rudimental maxilla ; Mr. Westwood (Introd. 

 etc II P 525), who makes this suggestion, adds, that the texture 

 of this fifth joint is different from that of the other four. The 

 last joint of the palpi is usually longer than the preceding, som - 

 wha linear; but, except in some rare cases, as "^ .^/^f •'«'/ /^ 

 Tever very long. Immediately under the part which I call the 

 epistoma, is a linear, pointed organ, called the tongue; it is espe- 

 cially long in Geranomy... Meigen (Vol. VI, p- 28), in d. t 

 ing the mouth of Glochina, also mentions a pair of hoii y, lui ar 

 pointed maxiUse. A comparative study of the parts of the mouth 

 of the TipuUdse is yet to be made. 



The eyes are oblong or rounded, separated a!,ove by a fiont 

 which is more or less broad in different genera but not percep- 

 tibly broader in one sex than in the other. On the uncle de 

 of the head, the eyes are usually more approximate, often almo t 

 contiguous. There is no striking difference in the size of the 



