1886] 149 



exhausting efforts, this larva got hoisted to the top of an enormous 

 stone (in proportion to the creature's size), which was fixed not so as 

 to close the case, but at the side evidently to serve as a point d'apj^ui 

 when the operculum came to be forced by the nymph. The fixing of 

 the case took place on May 20th, and the perfect insect appeared 

 June 7th. 



The larva is of a distinctly Leptoceridous type, from the great development of 

 the posterior legs. The head is almost round ; the prothorax transverse, vrith the 

 sides produced anteriorly into a tooth : these two segments are of a bright reddish 

 colour, while the rest of the body is white, or, in older examples, yellowish. The 

 body is rather slender, and tapers gradually to the anal extremity ; a slight fringe on 

 the penultimate segment ; crochets with bunches of hairs, and above them small 

 protuberances, bearing one or two bristles of great length, and a few shorter hairs ; 

 no external respiratory filaments. The legs are rather thickly clothed with long 

 silky hairs. 



Adicella filicornis, Pict. 



The habits of this pretty little species were known to Pictet, and 

 he has described and figured the larva and case in " Eecherches " (p. 

 171, pi. xii, fig. 6). 



I made the acquaintance of the perfect insect in June, 1884, and 

 and on April 8th of the present year found the cases iu small cavities, 

 where there was a constant trickle of water, and which were covered 

 with a facing of moss. The moss was, of course, moist, and on its 

 inner face the cases were fixed. They mostly contained nymphs. 

 Only two were found containing larvas, and I am not sure now whether 

 they came from the mossy roof, or from the floor over which the 

 water streamed ; they soon spun up, and the first insect came out on 

 May 16th. 



The cases are 8 to 10 mm. iu length, strongly curved and tapering, 

 composed of sand-grains on an inner tube of silk. They are usually 

 of a russet colour, but some are blackish in the older parts, as is usual 

 in cases of this form. They seem to be covered with a deposit of 

 some kind, which gives them a comparatively smooth appearance. 



The shape of the case of JB. pullata, the long legs and reddish 

 head of its larva, led me to suspect at first that Pictet had erred in his 

 identification of the larva of his Mystacides filicornis. There is a 

 superficial resemblance between the two in the points mentioned, but 

 the more elongate head and uncoloured prothorax of the larva of A. 

 filicornis are good differential characters, not to speak of its antennse, 

 which are developed to such a degree that they are distinctly indicated 

 in Pictet's figure, though he makes no reference to them in the text. 



