Mollaaca from the Bokkeveld Beds. 249 



arranged round tubercles ; the spaces between the ribs are broader 

 and show traces of longitudinal striation. There is a central weak 

 impressed line down each face. The rate of tapering of the shell is 

 about 1 in 3, and there are about 25-30 ribs in a space of 10 mm. 

 The length of this fragment of the shell is about 52 mm., and the 

 width about 26 mm. across the middle of the face which is pre- 

 served. The shape of the shell is like C. undidata, but the orna- 

 mentation appears to be coarser and to resemble C. congregata, Hall.'"' 

 Localities. —(No. 80) Above Koudeveld Berg. ? (No. 138) Uitkomst, 

 Ceres. 



CONULAEIA cf. ACUTA, F. Eoemer. 

 (PL XXX., fig. 11.) 



There are several fragments of a species of Conuhtria in which 

 the sides are covered by gently undulating small rounded ribs, 

 regularly arranged, numbering 27-30 in a distance of 10 mm., and 

 ornamented w^ith transverse, closely set, narrow, laterally com- 

 pressed, pointed, longitudinally oval tubercles which apparently 

 alternate on successive ribs. The riljs are separated by narrower 

 grooves crossed by low faint ridges in apparent continuation of the 

 tubercles of the higher rib. No well-preserved face of the shell is 

 shown in any of the specimens, but the arching of the ribs appears 

 to be very slight ; the centre of each face is marked by a narrow 

 impressed line, scarcely interrupting the continuity of the ribs. The 

 rate of tapering of the shell seems to be about 1 in 4. The angles of 

 the shell are rounded and infolded, but the shape of the transverse 

 section is doubtful. 



Affinities. — The European Lower Devonian species described by 

 Sandberger i as C. suhparallela appears to be allied to this form, but 

 the resemblance is not close. The figure given by Steinmann and 

 Doderlein ]: of C. acuta, Eoemer, from the Devonian of Bolivia, 

 indicates the same type of ornamentation as found in these South 

 African specimens, but Eoemer's § figure suggests rounder tubercles 

 on the ribs. Ulrich li compares a Bolivian form with Eoemer's 

 species. 



Locality. — (Nos. 75, 76, 77, 78, 79) Gamka Poort. 



* Hall, oj). clt., p. 214, pi. xxxiv., ti<,^ 1 ; p]. xxxiv.A, ti^s. 9-11. 

 t Sandberger, Verstein. rhein. Schichtensyst. Nassau, (1.S50-1856), p. 243, 

 pi. xxi., figs. 2, 2a, 2b, '6. 



X Steinmann and Ddderlein, Eleni. d. Paliiont., (IS'lO), p. 843, fig. 39oA and B. 

 § F. Roemer, Versteiner. d. Harzgeb. , (1843|, p. 36, t. x., figs. 12, 13. 

 II Ulrich, op. cit., p. 30, t. iii., figs, iia, oh. 



