64 



[No. 7. 



distinctly in those having summer-eggs. The inferior edges of 

 the valves exhibit the usual fringe of delicate bristles. 



The eye is rather small and of the same structure as in the 

 2 preceding species. 



The ocellus is comparatively large, and but very little, if 

 at all, smaller than the eye, subquadrangular in form and lo- 

 cated a trifle nearer to the eye than to the tip of the rostrum. 



The antennulae are of a slender conical form and on the 

 whole agree very nearly in structure with those organs in A. 

 lavimma; as in that species they reach almost to the tip of 

 the rostrum. 



The tail (fig. 8) differs somewhat in form and armature from 

 the two preceding species. It is comparatively short and broad, 

 more so even than in A. lavissima, and has the apex somewhat 

 obliquely truncated, with the posterior corner forming a very 

 distinct angle. The outer part of the dorsal edge is quite straight 

 and armed with a double series of very short but rather strong 

 equal-sized denticles, 8 or 9 in each row. There is no trace of 

 any lateral series of spines, as in the two preceding species. 

 The supraanal angle projects distinctly, and the dorsal edge 

 above it is, as usual, strongly chitinized. The caudal claws are 

 not very large, but exhibit, in common with the dorsal denticles, 

 a rather dark brownish colour; the secondary denticle at their 

 base is exceedingly small. 



As in A. Imvissima, numerous oil-globules are dispersed within 

 the body, exhibiting, however, in this species a very conspicuous 

 orange hue. 



The colour of the animal is pale yellowish or corneous, the 

 dorsal part of the shell being somewhat darker in specimens 

 provided with winter-eggs, though never assuming such a black 

 colour as in A. Archeri. 



The adult male (fig. 9) is, as usual, much smaller than the 

 female, scarcely attaining a length of 0.30 mm, and is distin- 

 guished by the carapace being considerably narrower, owing to e 

 much less arcuate dorsal edge. As in other species it fe> be ^' 

 sides, easily recognized by the strong, dark brownish-coloure 



