235 



an elevated base; mandibles similar to those of Rhyphidae in that they 

 consist of a stout basal piece and an articulated apical one, the latter 

 with several teeth; labium small, rounded anteriorly, the appendage 

 above it (mentum) similarly shaped, both armed with numerous hairs 

 (PI. XXXVI, Fig. 10) ; labrum overhanging oral orifice, the epi- 

 pharynx armed with numerous strong spinules; maxillae and their 

 palpi similar to those of Rhyphus punctatus; eyes pigmented, situated 

 on side of head instead of being on dorsum as in Rhyphus. Body 

 with short decumbent pile; segments of thorax bisected, those of ab- 

 domen trisected ; pseudopods absent ; apical segment with 4 finger-like 

 processes, the lower pair longer than the upper and furnished with 

 some delicate hairs at apices. 



The specimen described above was taken by A. G. Whitney on St. 

 Paul Island, Bering Sea, March 23, 1913, and formed part of a col- 

 lection submitted to me for identification by the U. S. Bureau of Bio- 

 logical Survey. 



Limnobiid Larvae of Uncertain Generic Location 



I have based the synoptic key to the larvae of the subfamilies upon 

 species that I have reliable identifications for, but certain larvae that 

 I have before me are not in agreement with the characters cited, or 

 they so vaguely resemble those that are identified as belonging to the 

 various subfamilies that I have deemed it wisest to describe them in- 

 dependently, in the hope that further light may be shed upon their 

 position in the classification by some student of the group who may 

 succeed in rearing them. 



I realize that there are in store for us many surprises in the larval 

 and pupal characters of species that are as yet unknown in these stages, 

 and hope that the present effort to assign characters for the separa- 

 tion of the subfamilies may be improved upon rapidly after it appears 

 in print. 



Genus incertus i 



Larva (PI. XXXV, Fig. 11). — Length, 10 mm. Golden yellow, 

 covered with silky hair which gives the larva a satiny appearance. Ta- 

 pering on thoracic segments towards head. Head almost completely re- 

 tractile, ventral aspect as in Figure 16, Plate XXXV; oesophagus con- 

 spicuous, its sides with very prominent ridges which meet angularly 

 in center; maxillary palpi 2-jointed, of moderate size; mandibles bare- 

 ly distinguishable in mount (see figure last mentioned) ; posterior 

 portion of head consisting of 4 rods, the dorsal pair more elongated 



