cook: web-spinning fly larvae 193 



At first he was inclined to believe that the spinning larvae might 

 belong to the family Tipulidae, but he now considers it more prob- 

 able that they are Mycetophilidae, as several other members 

 of this famih^ are known to spin webs or to live in web-like tubes 

 of slime. The larval characters of this group of flies are so little 

 known that a definite identification of the animals found in the 

 webs is at present out of the question. But as no webs of similar 

 construction seem to have been described, Mr. Barber has urged 

 me to publish my notes on the subject. 



The specimen secured from a web by Mr. Barber was somewhat 

 larger and somewhat tinged with brown or black, instead of being 

 entirely transparent hke mine. Whether it represented a more 

 advanced stage or a different species could only be conjectured. 

 Mr. Barber also remembered that there were beads of moisture or 

 slime on the fringing threads of the web, whereas my impression 

 was that the threads or rods of slime were cylindrical and of con- 

 stant diameter up to near the cable, where they were suddenly 

 narrowed. Such differences might depend on the humidity of 

 the atmosphere to which the webs were exposed. 



Nothing in the way of a specialized subterranean fauna was 

 found in the caves, unless it be the larvae that spin these webs, 

 and even these may not be confined to the caves. Other webs that 

 may have been made by the same kind of larvae were seen after- 

 ward in open recesses in the side of cliffs along the road between 

 Senahii and Sepacuite, tho not in condition to compare with 

 the much more perfect structures seen in the eaves. 



