SYR I' 1 1 I DAK. OI-' M \l \ K. j | | 



Rudimentary prolegs present. Anterior pupal respiratory 

 cornua elongate, cylindrical, very prominent. 



This type is most closely allied to tin 1 third type hut differ- from 

 it and from all the others in the rernark:ihle elongation of tiie po>- 

 terior respiratory organ, which, in these species, i> tube-liki-. :hn-e 

 jointed and telescopic; and may he extended to several tinn 

 length of the body although commonly contracted to ah'>n; 

 length. This remarkable and highly speciali/ed organ etiahles tin- larva 

 to carry on aerial respiration while feeding- at various depths h< 

 the water level. It is of two tubes fused mesad and enclosing two 

 tracheae which open at the tip. The inter-spiracular ornaments 

 sist each of a single, unbranchcd, hut plumose, long hair in-trad : : 

 palmate group of short plumose hairs as in the two previous type-. 

 The prolegs are similar to type III. The anterior larval -;>. 

 unusually conspicuous, borne on a pair of cornua which are capable 

 of considerable elevation although usually rather closely retracted. 



The shape of the body is sub-cylindrical with the anterior segi 

 forming a false head, and the mouth-hood as in type III. The terminal 

 segment tapers strongly into the respiratory process. The integument 

 is very flexible and transparent; segmental hairs double, similar to 

 type III. The anterior pupal cornua are longer than in type III and 

 nearly cylindrical, the enlarged distal part much longer than the ba-al 

 stalk, hence the whole less mushroom-shaped. 



V. THE MICRODON TYL'I- OF LARVA. 



Body hemi-spherical; the flat surface ventrad, with a row of 

 spines around its margin; dorsuni reticulated. Posterior respi- 

 ratory process short, the three spiracles on each half together 

 making nine loops, convex outwardly and denticulated on their 

 outer margin. Inter-spiracular ornamentation of non-plumose 

 fine hairs. Mouthparts consisting of a ventral \-shaped /<;: 

 and tzvo dorsal pieces placed \-sluipcd. hut not fused at the 

 apex. Segmental hairs and prolegs wanting. Anterior larviil 

 spiracles apparently wanting. Pupal respiratory cornna ;// rcl 

 shaped. 



The larvae of this genus are very aberrant and superficially show 

 no relationship with the other larva- of Syrphidse, differing ?tri 

 from all the others in shape. Instead of the elongate, sub-cylindrical 

 body we have a nearly hemi-spherical body. The outline is 

 elliptical, the ventrum very much flattened forming a ventral 

 around the margin of which is a circlet of ornamental spines. l)or-nm 

 almost uniformly rounded up. Mouthparts open in a longit 

 on the cephalic part of the ventral sole. Posterior respirato 

 dorso-caudad, short, tubular, but with -rime indication >>: i 

 nature; circular plate medio-dorsad. The -piraoular - 



