On Fresh-water Entomostraca. 37 



vided at the tip with a bundle of somewhat unequal olfactory 

 papillæ, and have, moreover, each a delicate sensory bristle 

 projecting from the anterior edge about in the middle. 



The antennæ are well developed, and exhibit the normal 

 structure. 



The lamellar expansion of the labrum is of moderate 

 size, and exhibits the usual securiform shape, its edge being 

 quite smooth. 



The tail (fig. 2) is rather large, lamellar, and almost of 

 equal breadth throughout, or but very slightly expanded 

 distally, being obtusely truncated at the end, with the pos- 

 terior comer rounded off. The post-anal angle is rather 

 indistinct, nearly obsolete, and the posterior edge below it, 

 very slightly convex, exhibiting a double row of well-defined 

 denticles, about 15 in each row. Somewhat within the edge, 

 moreover, occurs on each side a lateral row of very deli- 

 cate, somewhat squamiform denticles, corresponding in num- 

 ber with the marginal ones. The terminal claws are rather 

 strong, and each armed at the base with a comparatively 

 large secondary denticle. 



Occurrence. — The above-described specimen, the only 

 one I have seen, was found in a sample taken by Mr. 

 Whitelegge from the Centennial Park, near Sydney. 



16. Alona pulchella, King. 



(PL 6, figs. 3, 4). 



Alona pulchella, King, 1. c. p. 260, Pl. VIII B. 



Specific Characters. — Shell, seen laterally, oblong 

 quadrangular, not widening at all behind, posterior extremity 

 obtusely truncated, with the lower corner rounded off, dor- 

 sal margin evenly arcuate, ventral straight. Head sub-erect, 



