308 Annals of the South African Museum. 



4. DAPHNIA CORONATA, n. sp. 

 (Plate XXX, fig. 1, !-/.) 



Specific Characters Female. Carapace, seen laterally, oval iu out- 

 line, with the spine rather coarse and turned obliquely upwards, origi- 

 nating considerably above the axis of the body. Head comparatively 

 large, with the occipital part produced above to a hump-like protuber- 

 ance, front rounded below, inferior edge straight ; rostrum short and 

 obtuse, resembling that in the two preceding species. Dorsal denticles 

 of carapace rather coarse and arranged in a double series extending far 

 iu front, and on the occipital part of the head diverging to encircle a 

 somewhat lozenge- shaped area just behind the hump-like protuberance. 

 Eye of moderate size. Antennulae small, resembling in structure those 

 in the two preceding species. Tail-piece exhibiting a similar form to 

 that in D. dolichocephala, but having the apical claws comparatively 

 larger and the anal denticles more coarsely developed. 



Length of shell (without the spine) reaching 2 mm. 



Remarks. The above-described form is closely allied to D. dolicho- 

 n-jJiala, and indeed at first I was inclined to regard it as merely a 

 variety of that species. On a closer examination, however, I have 

 found that it ought to lie distinguished specifically, as it differs very 

 conspicuously in the shape of the head and more particularly iu the 

 peculiar ornamentation of the occipital part, which latter character has 

 suggested the specific name here proposed. A somewhat similar orna- 

 mentation is also found in the form at first recorded by Dr. Eichard 

 under the name D. bolivari, but subsequently considered by that 

 author to be a variety of D. atklnsoi/i, Baird, as also in the peculiar 

 form described by the present author from the Central Asiatic lake 

 Tenuice as D. triquetra. The present form is, however, otherwise very 

 different from either of these two species. 



Occurrence. Numerous specimens of this Daphnia (most of them 

 still immature) were contained in an alcoholic sample kindly sent to 

 me by Dr. Purcell, who procured it from a pond in the Karroo at 

 Ashton, Robertson Division, August 26th, 1900. All the female 

 specimens exhibited the same characteristic shape of the head 

 and the same peculiar ornament of its occipital part. In the male, 

 however, of which only a single specimen was found, this ornament 

 was wholly wanting, as seen from the fig. I/ on the accompanying 

 plate. 



