CLADOCERA AND HALOCYPRID AB. 
By G. Stewarpson Brapy, M.D., LL.D., D.Sc., F RS. 
(Plates XVI and XVII.) 
CLADOCERA. 
Genus SIMOCEPHALUS Schoedler, 1858. 
SIMOCEPHALUS GELIDUS sp. nov. 
(Plate XVI, figs. 10-13.) 
Seen laterally the shell is elongated, fully twice as long as broad ; head rounded 
in front and produced ventrally in a straight line to a sharply prominent backward- 
pointed beak. Dorsal margin almost straight throughout, ending abruptly in an obtuse 
angle; ventral margin gently arched in front and continued with a distinct curvature 
to the well-marked postero-dorsal angle. Seen dorsally or ventrally the outline of the 
shell is almost circular, the head forming a very prominent rounded segment in front. 
Dorsal processes of the abdomen well developed, the two proximal ones stout and 
strongly curved in opposite directions; pre-anal spines twelve in number, separated 
into two distinct series of six each; terminal unguis ‘slender, without serratures or 
marginal fringe. Length, 2-5 mm. 
Taken plentifully in fresh water on Macquarie Island by Mr. H. Hamilton. 
The Rev. R. L. King in a paper on the Daphniade of New South Wales* describes 
very shortly, and figures Daphnia Elizabethe, a species which evidently approaches 
very closely that now described under the specific name gelidus, but the shape of the 
shell as also the spinous armature of the postabdomen do not allow of identification 
with that species. 
Daphnia cavicervix, described by Dr. Sven Ekman bears some resemblance to 
this species, but the furcate spines of the postabdomen together with the conspicuously 
fringed terminal claws sufficiently distinguish it from S. gelidus. 
Genus Cuyporus Leach. 
CHYDORUS MACQUARIENSIS sp. nov. 
(Plate XVII, figs. 17-19.) 
This might very readily be taken on a casual glance for Chydorus piger, G. O. 
Sars, as figured by Prof. Lilljeborg in his work on the Swedish Cladocera. But it 
*Papers and Proceedings of the koyal Society of Van Diemen's Land, 1853. 
+Cladoceren aus Patagonien (Zoologisches Jahrbuch, 1900). 
