216 Annals of the South African Museum. 



approximately straight outlines in the anterior half and converge 

 very gradually at first, but more rapidly in the vicinity of the 

 narrowed, rounded, posterior margin. The anterior margin is almost 

 straightly transverse, and forms roughly rectangular junctions with 

 the sides. The dorsal surface of the telson is of flattened form, 

 curving down abruptly at the lateral margins. There is a weak 

 median longitudinal ridge which dwindles away posteriorly before 

 reaching the hinder border. At a distance of about one-quarter of 

 the total length of the telson from its anterior border there arises 

 from the median ridge on either side a curved, narrow ridge, bearing 

 granules or minute tubercles. These first pass backwards, and, 

 diverging from the median ridge, they curve outwards and pass 

 obliquely forwards to the antero-lateral angles of the telson. Each 

 encloses a roughly ovate area of the dorsal surface which is almost 

 smooth, or has very sparse granular ornaments. The remainder of 

 the surface of the telson has evenly spaced granules or minutely 

 tubercular ornamentation. 



The appendages of the abdominal segments are unknown, except 

 portions of the expanded swimming organs of the sixth segment ; but 

 these are too imperfectly preserved for precise description. 



Dimensions. The largest specimen examined measures 38 mm. 

 along the median dorsal line from the tip of the rostrum to the 

 posterior end of the carapace. The greatest height of the carapace 

 in this specimen, if it were perfect, would be about 16 mm. Other in- 

 dividuals, in which the rostral region is absent, have a similar height- 

 measurement, and the total breadth of their carapaces measured 

 in cross-section does not appear to exceed 8 mm., although the 

 specimens have not suffered appreciably from lateral crushing. The 

 length of the abdomen in extension cannot be accurately measured 

 owing to the flexion assumed at death, but it may be estimated to 

 have been approximately the same as that of the carapace. 



Occurrence. Several specimens were obtained by Mr. Rogers 

 from a bare slope W. 30 S. from the middle of Barkly Bridge, on 

 the farm Olifant's Kop (35h, 37h, 38h). 



A specimen consisting of portions of a thoracic limb which 

 may belong to this species is from the collection of the South 

 African Museum and is labelled "Sunday River " (663, on white 

 label). 



Remarks. Since the term " epimeron " has been used in two 

 distinct senses by different authors, the term " pleuron " has been 

 retained in the above description to denote the downward lateral 

 prolongation of the tergum of each abdominal segment on either 



