OX THE ORAL APPARATUS OF THE LARVA OF WORMALDIA. 115 



VI. 



ON THE ORAL APPARATUS OF THE LARVA 

 OF A\ ORMALDIA, A GEXUS OF TRICHOPTERA. 



BY KENNETH J. MORTON. 



With one Plate [II]. 

 [Read 22nd February, 1887.] 



My chief object in giving some account of the larva 

 of Wormaldia is to direct attention to the structure 

 of the mouth parts, especially of the labrum, which 

 has no parallel amongst the larvae of Trichoptera that 

 have hitherto come under my notice. It may be well 

 to say the determination of the genus is based on 

 evidence more collateral than direct, as I have not 

 yet succeeded in rearing the perfect insect. 



Usually where the waters of small springs find 

 their way with rather rapid and shallow flow over 

 rocks into larger streams, these larvae are to be 

 found. In a locality of this nature in our neigh- 

 bourhood. I have met with them very commonly 

 in April, when they live in webs loosely spun 

 amongst stones. Later, in cases formed of small 

 stony fragments heaped together and fixed to larger 

 stones, I have found the same larvae evidently ready 

 for metamorphosis, and from such a case I have 

 reared Wormaldia occipitalis, Pictet. As no other 

 Hydropsychid seems to frequent the spot, the chance 

 of error as to the species is not great. 



The general appearance of the larva of Wormaldia 

 is quite similar to the figure Pictet gives of that of 

 his Hydropsyche montana (=Philopotamus montanus. 

 Don.), RecJierches, 210, pi. xviii., fig. 5 ; but by this I 

 do not mean to imply a possible error on Pictet's 

 part, as Pliilopotamus and Wormaldia, being allied 

 genera, may well have larvae agreeing in facies.. 



