tapered distally. Urosome with the segments finely spinulose at the hind margin 

 ventrally and laterally, last segment much shorter than the preceding one. Caudal 

 rami exceedingly short, being about twice as broad as they are long, middle 

 apical setae slightly thickened at the base, seta of outer corner unusually strong, 

 spiniform. Anterior antennae comparatively short, 8-articulate, 4th joint scarcely 

 longer than 3rd, terminal part not attaining half the length of the proximal one. 

 Outer ramus of posterior antennae with the middle joint very small and without 

 any seta. Oral parts quite normal. 1st pair of legs with the outer ramus ex- 

 tending somewhat beyond the middle of the 1st joint of the inner, middle joint 

 without any seta inside, last joint of about the same length, and carrying on the 

 tip only 2 spines and 2 geniculated- setae ; 1st joint of inner ramus slender, linear, 

 and about twice as long as the other 2 combined, last joint twice as long as the 

 2nd, apical claw slender and nearly straight. Natatory legs with the rami very 

 narrow and the setae of the inner edge much reduced in number: 1st joint of 

 outer ramus in all pairs without any seta inside; last joint of same ramus in 

 2nd pair having the inner edge also quite smooth, and in the 2 succeeding 

 pairs carrying only a single seta inside; last joint of inner ramus in 2nd and 

 4th pairs with a single seta on the inner edge, in 3rd pair with 2 setae. Last 

 pair of legs with the distal joint oval in form, and provided with only 5 marginal 

 setae, that issuing from the tip being very slender and quite smooth; inner ex- 

 pansion of proximal joint rather large, extending about as far as the distal joint, 

 marginal setae rather coarse and 5 in number. Ovisacs comparatively large, but 

 containing a rather limited number of ova. 



Male with the anterior antennae transformed in the usual manner. 2nd 

 basal joint of 1st pair of legs produced inside to 2 strongly chitinized diverging 

 projections. Inner ramus of 2nd pair fully as long as the outer, distal joint pro- 

 duced at the end to a strong mucroniform projection not denned from the joint. 

 Last pair of legs much smaller than in female, with only 2 setae on the inner 

 expansion of the proximal joint. 



Body of a whitish colour, with a slightly reddish tinge, intestine generally 

 of a dark violaceous hue. 



Length of adult female 0.46 mm. 



Remarks. This form has been very minutely described and figured by 

 Dr. Giesbrecht as a species of the gen. Dactylopus. It belongs, however, beyond 

 doubt to the genus Ampluascus, as here defined, having, like the other species, 

 2 ovisacs. The species is chiefly characterised by the comparatively short anterior 

 antenna?, and the considerable reduction in the number of the natatory setae on 

 the legs. 



