84 LARVA OF TANYPUS MACULATUS. 



suppose that there are two distinct flies with two distinct larvae, 

 we find in his specific description of the perfect insects, that 

 Tanypus moJiilis is synonymous with De Geer's Tanypiis macula- 

 tus, ^ and also with that of Latreille, t the larvae of which in 

 either case, as evidenced especially by De Geer's figure, are 

 identical with one another and with mine. Whatever may be the 

 explanation of this paradox, the Tipulid larva I purpose here to 

 deal with was known to De Geer as that of Tanypus maculatus^ 

 and was described by Walker under the name of T. monilis. It 

 is a type of a number of somewhat similar larvae, none of which, 

 so far as I can find, have ever been described, and whose habits 

 and transformations are, I believe, entirely unknown. Its minute 

 size and the transparency of its tissues render it especially adapted 

 for microscopic study, and as a starting point for the study of 

 other allied forms. 



The larva (PI. 8, Fig. 7) is composed of 13 segments, 

 including the head, which is distinguished by the denser and 

 yellower character of the integument, upon which are situated a 

 pair of conspicuous eye-spots. The front of the head (Fig. 8) 

 exhibits a pair of setaceous organs, which I must be content to 

 describe as antennae, though I am doubtful as to their function. 

 They appear to occupy the place which undoubted antennae do in 

 other species, but they have two peculiarities which seem to 

 remove them functionally from those organs : — firstly, they are 

 retractile, having a muscle at their base by which they are occa- 

 sionally withdrawn a considerable way into the head, from which 

 they can be again protruded by some unknown agency ; and 

 secondly, they seem to be furnished at the base with a saccular 

 organ, reminding one of the poison-gland of spiders. Both of these 

 features lead me to regard them as lethal weapons, whatever may 

 be their homological relations. In the same situation, also, we find 

 a pair of strong mandibles (Figs. 8 and 20), and between these 

 appear a pair of pointed maxillae, the inner basal angle of which 

 is furnished with an appendage consisting of a group of pyriform 

 cells (Fig. 17), a feature so strange that I was doubtful at first 

 whether they were not minute Vortlcellce, till prolonged observa- 

 tion convinced me to the contrary. I have never seen anything 

 similar in any other insect. Below the maxillae is seen the 

 labium, the front edge of which is raised into a number of little 

 rounded projections. 



Perhaps one of the most striking features of this and similar 

 larvae are the singular grappling appendages, which supply the 

 place of feet (Figs. 7, 10, and 12). Two pairs of these are found, 



* De Geer, Mem., Tom. vi., Plate 24, Figs. 15 — 19. 

 t Hist. Nat. des Cruse et Insect, Tom. iv., p. 248. 



