The Anal Feet of Caddis-ivorms 35 



appendages were seen. It is therefore possible that the 

 prothoracic and anal feet of a Chironomus-larva may be 

 the remnants of a series which once extended over many- 

 segments ^. 



In the larva of Simulinm both the prothoracic and the 

 anal' feet are recognizable, though they are largely fused, 

 especially the anal pair, which constitute the posterior 

 sucker. 



Caddis-worms, which also inhabit tubes of various The anal 

 materials woven together, possess a pair of hooked feet at ^^®,*^/-* 

 the hinder end of the body, and hold on by means of worms" 

 them, in the same way as Chironomus-larvae. 



The eleventh segment of the Chironomus-larva has two Biood-giiis. 

 pairs of ventral apjjendages, which are slender, thin- walled 

 and tubular ; these are believed to be respiratory ; they 

 are wanting in fresh-hatched larvae, as also in the surface- 

 haunting species. 



From the dorsal surface of the twelfth segment project Appen- 

 two bunches, each of five long setae. With each bunch thfiaslseg- 

 a small ganglion is associated, so that they are apparently ^^^ " 

 sensory in function 2. Close to the anus are two pairs of 

 small anal papillae, or blood-gills (see figs, i, 24). These 

 are tubular, and, we believe, respiratory. In some species 

 a long seta springs from the base of each papilla of the 

 upper pair. Either end of the body may require to be 

 protruded from the tube ; each is therefore furnished Avith 

 organs for holding on and for perception. There are 

 respiratory organs only at the tail-end, for these can be 



' As these sheets are passing through tlie press, Mr. T. H. Taylor lias 

 reared the fly from the larva described above, v^liich is the hitherto 

 imknown larva of Clinocera (fam. Empidae). Some Hemerodromia-larvae 

 are similar, but have only seven pairs of pseudopods. 



^ In the larva of Tanypus (fig. 21) two similar bunches of filaments are 

 carried on long cylindrical joints. The larvae of two undetermined 

 species of Chironomus, which burrow in the leaves of Potamogeton 

 natans, show tufts of setae, standing out from the sides of most of the 

 segments. The thoiacic segments and the twelfth abdominal segment 

 in one species, the prothorax and the last two abdominal segmeats in 

 the other, have no such tufts. The dorsal sensory tufts of ordinary 

 Chironomus-larvae may be serially homologous with these. 



D 2 



