208 Annals of the South African Miiscum. 



The thorax which seems to helong to this head, is represented in 

 Salter's fig. 9, and several more or less perfect specimens occm- in 

 the collection under description. The axis is broad, forming about 

 one-third of the width, and diminishing rather rapidly after the sixth 

 segment ; it was not provided with axial spines. The pleurae are 

 deeply grooved and bent downwards at about one-third of their 

 length from the axis, and the hinder ones are produced into spines. 



Tail semicircular in outline, arched. Axis prominent, does not 

 reach the posterior margin, and terminates obtusely ; it bears seven 

 ribs, of which the first three are very distinct but the last three or 

 four tend to become obsolete. Lateral lobes arched downwards, 

 with five deep narrow grooves separating the wide fiat ribs, and 

 these ribs are divided by fainter furrows upon their surface ; the 

 grooves do not reach the margin. There is no distinct border, but 

 the margin is produced into short points, of which there appear to 

 be four, or perhaps five, on each side. • 



Bomarks. — The type of the species is the specimen figured by 

 Salter in pi. xxv., fig. 6, which is now in the British Museum, along 

 with several other precisely similar heads from the same locality 

 (the Cedar Mountains). Salter's fig. 9, also in the British Museum 

 and from the same locality, appears to be the thorax and tail of this 

 species. 



In the collection under description there are several specimens of 

 the thorax and tail, and one imperfect head with the first seven 

 segments of the thorax attached. 



The form was considered by Salter to be the same as P. africanus, 

 but this was probably due to the comparatively small number of 

 specimens of the latter which he had at his disposal. There can be 

 no doubt that the two species are quite distinct, and the differences 

 between them have already been pointed out in the account of 

 P. afn'caiius. In his figure of the head Salter inserts, in dotted out- 

 line, occipital and genal spines, but of these neither the type specimen 

 nor any of the other heads from the same locality shows any trace 

 whatever. 



Affinities. — As Salter ■•'■ points out, the compact hal)it and convex 

 tail differentiate this African species from the typical forms of 

 Cryphams ; and it is probable that a new subgenus should be made 

 for this and the following species. 



Localities.— Gd,m\^ Poort (33, 36, 39, 42, 58, 65). Also from the 

 Cederberg (specimens in the British Museum). 



* Monog. British Tiilobites, I'al. Soc, 18(54. p. 1-j. 



