90 " [September, 



indeed, they rarely survive such an immersion more than a few hours. 

 Thus any attempt to rear them should be made in a wide vessel with 

 very shallow water, if a mechanical contrivance for keeping the water 

 in a highly aerated condition cannot be employed. Pictet knew the 

 larva and nymph of one or more species, and gives some interesting 

 account and figures in the "Becherches." 



The larvae do not make any case worthy of the name, but live 

 concealed in large loose webs spun between stones. The nymph cases 

 on the other hand are strong structures, elongate heaps of compara- 

 tively large stony fragments fixed to large stones, with a silken lining 

 which forms a complete envelope round the nymph. 



The larva of Ph. montanus has the head and pronotnm orange, the 

 latter margined laterally and posteriorly with black ; legs yellowish, 

 with blackish markings at their insertion ; anal claws also yellowish ; 

 meso- and meta-thorax whitish. In form it is elongate, and the abdo- 

 men, whose segments are well defined, tapers gently to the posterior 

 end. Seen from above the head is elongate, slightly emarginate in 

 front ; antennae minute, seen under a high power apparently consisting 

 of two short, simple branches.* Pronotum somewhat quadrate, 

 slightly narrowed posteriorly. The two other thoracic segments differ 

 from the abdominal ones only in being a little larger. The legs are 

 short, the pairs nearly equalling one another in length ; tarsal claws 

 very short. The anal limbs are rather short and stout, with a strong 

 much curved claw. Anal filaments present, but no lateral filaments. 

 The whole larva sparsely covered with hairs. Of the mouth parts the 

 most remarkable is the labrum, which resembles the same part in 

 Wormaldia, but is less conspicuous in comparison. It is white, and 

 appears to be of softer consistency than is usual in Trichopterous 

 larvae ; when fully exserted, it expands into two transverse lobes, with 

 closely ciliated fore-margins and a long fringe at the side. Mandibles 

 large and falcate, the tip forms a large tooth ; going towards the base 

 follow two smaller teeth, then an indistinctly crenate part ; about half 

 way to the base the mandible is obtusely angulate and -becomes 

 broader. First maxillae with four-jointed palpi, laciniae. strongly fringed 

 and armed with spines. The other parts form the spinneret, which is 

 large, obtuse and provided with minute processes, which may represent 

 the palpi of the second maxillae. The nymphs approaching maturity 

 are easily made out, especially the £ , the anal parts of which closely 

 resemble the corresponding parts of the perfect insect, as is the case 



* Similar to those of Wormaldia, which Fhilopotamus much resembles in all respects. At 

 description of Wormaldia will be found in Trans, of Nat. Hist. Soe. of Glasgow for 1886—7, 

 p. 115 (I think, not yet published). 



