ON A NEW ICHTIIYOXENUS FROM LAKE BIWA. 



I27 



Metasome segments slightly increase in length posteriorly, except the 

 sixth or terminal segment which is very large, somewhat broader than 

 long, nearly flat and half-moon-shaped.^ The first two metasome segments 

 are visible in the middle parts only, the lateral parts being covered over 

 by the last mesosome segment. 



Mandible (fig. 3) slender ; anterior end narrow and rounded, with a 

 short claw-like process ; a comparatively large, internally directed process 

 present near the end. A moderately large, 3-jointed palp on the outer 

 side ; proximal joint the largest, distal joint the smallest. The palp bears 

 no hair, but shows a few (2 or 3) very minute processes, probably of 

 sensory nature, at the free end. In both sexes, tips of palps visible from 

 the dorsal side. 



Maxillula (fig. 4) very simple, rod-like, 

 distally slightly tapering, the tip provided with 

 four claw-like processes, of which the largest is 

 conspicuous on account of its brownish colour. 



Maxilla (fig. 5) finger-like, much stouter 

 than maxillula, with minute subterminal seg- 

 ment. Tip of maxilla bears a few (4 or 5) 

 recurved hooks. 



Maxilliped (fig. 6) also simple, consisting 

 mainly of two joints, of which the proximal 

 about twice as large as the distal. Dorsally, 

 to tip of the latter, is attached a rudimentary 

 joint, bearing at its inner end three or four 

 conspicuous recurved hooks. No endite pre- 

 sent on the proximal joint. 



Thoracic legs divisible into anterior and posterior groups, the former 

 consisting of three leg pairs and the latter of four pairs. In the anterior 



Fig. 3, Mandible, p palp. 



Fig. 4, Maxillula. 



Fig. 5, Maxilla. 



Fig. 6, Maxilliped. 



All from Jj>. Magri, about 24 X 



1) In Ichthyoxemts japcuevsis, the terminal segment is usually a little longer than broad, and 

 more or less cup-like, the free margin being distinctly curved ventrally. 



