The Trilobites of the Bokkeveld Beih. 211 



composed are distinctly visible. Each segment is produced into a 

 strong spine, of which there are five on each side. The actual end 

 of the tail is imperfect, but seems to have been rounded. 



Remarks. — The head of this species bears a close resemblance to 

 the small head figured by Salter as a young Phncops caffer {Joe. eit., 

 pi. XXV., fig. 10) ; but the axial furrows are considerably deeper, and 

 the frontal lobe is much more swollen. In these respects it 

 resembles his fig. 11, which Salter looks upon as the adult form. 

 The tail which I have ascribed to this species occurs oii the same 

 block as the head, and another similar tail with thoracic segments 

 attached comes from a neighbouring locality. 



The specimen on which Salter based his description of the thorax 

 and tail of Phacops caffer (see his fig. 13) does not seem to l)elong to 

 the same species, and is probably P. impresHus. The portion of the 

 head which is attached to this specimen differs considerably from 

 both his fig. 10 and his fig. 11. 



Affinities. — Phacops caff'er is a true Cryphmis, and very closely 

 resembles Cryphceus giganteus, Ulr.,''' from the Devonian of 

 Chahuarani in Bolivia. The tail is almost indistinguishable, except 

 that in the Bolivian form it is considerably more arched and is larger 

 than in most of the African specimens. 



The head of Cryphmis jxiituna, Hartt & Rathb., figured l)y J. M. 

 Clarke f from the Devonian of Brazil, also presents some resem- 

 blance to that of P. caff'er. 



Localities. — Ezelfontein, Ceres (18) ; Laken Vley, Ceres (20) ; 

 Wolvaarts farm near Ceres Village (34). Specimens 19 (Ezelfon- 

 tein), 31, and 32 (Laken Vley) may belong to the same species, but 

 are considerably larger. 



PHACOPS ? sp. 

 Plate XXV., fig. 5. 



There is a large thorax and tail from Keurboom's River which 

 presents very peculiar features. Similar specimens are to be seen 

 in the Museum of the Geological Society of London and also in the 

 British Museum ; but us no head is known it is impossible to deter- 

 mine even the genus with any certainty, and the reference to PJiacops 

 is entirely provisional. 



* Xeues .Jahib. Beil.-Band viii., 1.S93, p. 14. 



t As tiilobitas do ■■rez de Ereie e Maecam, Esbulo do Para, Brazil, p. 39, pi. 1, 



li;?-!. 13, 1(5; Ilj.-. Ma^. X,i3. Rio d? .fan?iro, vol. i , is;)-). Clarke's paper seems to 



have been separately published in 1890. - . 



