r//^' Trilobitcs of the. Bokkeveld Bech. 207 



to be confounded, and which was indeed included by Saltei' under the 

 same name, is Phacops ocellus, sp. nov. In the latter, however, 

 the fii'st and second glabellar furrows are much better marked, the 

 eye is smaller and set more forward, the genal angles are rounded, 

 and there is no occipital spine. The tails are also easily distinguished. 

 In Phacops ocellus the axis is not nearly so prominent as in P. afri- 

 canus, it does not reach the margin and it bears fewer ribs ; the 

 markings on the lateral lobes are much more definite in P. ocellus 

 than in P. africanus, the ribs in the former being broad and flat and 

 separated by deep and narrow grooves, while in the latter the ribs 

 are narrow and but little prominent and the intervening furrows are 

 wide, concave, and shallow ; in P. ocellus, moreover, the margin is 

 produced into short points, in P. africanus it seems to be entire. 



P. africanus appears to be closely allied to Acaste devonica, Ulr.," 

 which occurs in the Devonian of Chahuarani in Bolivia ; but in the 

 latter the head is considerably longer in proportion to the width, the 

 glabella is nearly parallel-sided and its frontal margin is rounded in 

 outhne. 



Like the Bolivian form, P. africanus may probably be referred to 

 the sub-genus Acaste. 



Localities. — ^Hex River Pass, along railway (2G) : Gamka Poort 

 (■27, 5G, 57, 07, 222). 



PHACOPS OCELLUS, sp. nov. 



Plate XXIV., figs. 9, 10. 



18oG. Phacops {Criipluens) africanus, Salter (pars), Trans. Geol. 

 Soc, ser. 2, vol. vii., p. 218, pi. xxv., figs. 6, 7, 9 only. 



Head somewhat triangular in outhne, genal angles rounded. The 

 glabella is nearly parallel-sided, its frontal margin forming an obtuse 

 angle ; it is considerably wider than the cheeks and is separated 

 from them by very shallow furrows ; the glabellar furrows are all 

 distinct, the first oblique, the second curved with the concavity 

 directed backward, and the third also curved Init with the concavity 

 forward ; the third is much deeper than the others. The occipital 

 furrow is strong and equally defined throughout its axial portion, 

 curving forwards in the middle. The neck segment is smooth and 

 bears no spine. Eyes small, placed near the glabella and very far 

 forward, opposite the first lobe of the glabella. 



* Neues .Jahrb. Beil.-Biind viii., ItJUiJ, \>. 21. 



