1904.] ENTOMOSTRACA FROM NATAL. 127 



This intei^sting species seems to occupy an intermediate position 

 between Herpetocypris and Stenocypris so far as the antennal setse, 

 at least, are concerned, but from the shell-charactei'S alone one 

 would undoubtedly assign it to Stenocypris. Pi'ofessor G. 0. Sars in 

 his description of ^S*. chevretixii mentions the " paitly denticulated " 

 spines of the lobes of the fii'st pair of maxillee, but does not figure 

 them, and the antennal setse of that species ai'e certainly much 

 more fully developed both as to length and number than in 

 JS. perarmata. These points I have been able to confirm from an 

 examination of British specimens of S. chevreuxii, which I have 

 been fortunate enough to find in several localities : — very 

 sparingly in a pond at Pike's Hill, and in the Hatchet Pond, both 

 near Lyndhurst, and more recently in considerable quantity in 

 ditches near the River Arun at Arundel, Sussex. Figures of the 

 shell, antenna, and post-abdomen of >S'. chevreuxii are given in 

 Plate YIII. figs. 58-62. 



Macrothrix affinis, n. sp. (Plate VIII, figs. 63-65.) 



Body short, length about one-third greater than the breadth 

 (fig. 63). Head short and obtuse, with a rounded angle to which 

 the antennules are attached ; dorsal margin gently arched, 

 obscurely angulated at its junction with the posterior margin 

 which is finely denticulated, ventral margin convex and fringed 

 with rather long hairs : antennules (fig. 64) club-shaped, slightly 

 dilated and truncated distRlly, crenulated on the outer margin 

 which bears a few cilia, as also does the truncated extremity. 

 Post-abdomen (fig. 65) spinulose along the whole of its posterior 

 border and having a short terminal hooked claw. The antennie 

 have the normal structure, not presenting any special characters, 

 nor does the shell exhibit any definite ornament or sculpture. 

 Length 0"32 mm. 



This is a very small species, and is not very unlike the Northern 

 M. laticornis, though only about half its size. 



EXPLANATION OF THE PLATES. 



Plate VI. 



Cjjclops gihsoni, $ , p. 123. 



Fig. 1. Seen from above. 



2. Antennvile. 



3. Mandible. 



4. Maxilla. 



5. Anterior footjaw. 



Fig. 6. Posterior footjaw. 



7. Foot of first pair, 



8. Foot of third pair. 



9. Foot of fifth pair. 

 10. Furca. 



Cyclops jpiisillus, 5 J P- 122. 



Fig, 11. Seen from above. 



12. Antennule. 



13. Antenna, 

 14... Maxilla. 



Fig. 15. Anterior footjaw. 



16. Posterior footjaw. 



17. Foot of first pair. 



18. Foot of fifth pair. 



Ectoci/clops ruhescens, ? , p. 124. 

 Fig. 19. Seen from above. | Fig. 20. Antennule, 



