40 Gr- O. Sars. 



Mr. King collected the species at Varroville, near Denham 

 Court, and also at St. Leonards, near Sydney. In the 

 samples taken by Mr. Whitelegge, this species did not occur. 



17. Alona abreviata, G. O. Sars, n. sp. 

 (Pl. 6. figs. 5, 6). 



Specific Characters. — ^ Shell comparatively short 

 and stout, and, seen laterally, of irregular quadrangular form, 

 broadest in front of the middle, posterior extremity trans- 

 versely truncated, dorsal margin abruptly curved in front, 

 ventral slightly convex anteriorly. Head somewhat flattened 

 above, semi-erect, terminating in a rather prominent, acute 

 rostrum Surface of shell sculptured in its posterior part 

 wiih obliquely longitudinal lines, which are somewhat flexu- 

 ous, so as to form an indistinct reticulation, anterior part 

 of valves transversely striated, inferior edges ciliated. 

 Ocellus smaller than the eye. Lamellar expansion of the 

 labrum with a distinct notch anteriorly. Tail short and 

 stout, obtusely truncated at the end, with the posterior 

 corner evenly rounded, and armed on each side with about 

 10 well-defined denticles, post-anal angle rather prominent, 

 and occurring at about the middle, terminal claws of moder- 

 ate size, and each armed with a small secondary denticle. 

 Colour pale corneous. Length of adult female 0,37 mm. 



Remarks. — This form, at the first sight, looks very 

 like the New Zealand species, A. macrocopa, described by the 

 present author in another paper, but differs, on a closer com- 

 parison, in the somewhat different sculpture of the shell, 

 as also in the minor development of the autennæ. Both 

 these species form, as it were, a transition to the genus 

 Alonella, though being distinguished from the species of 



