552 Dr. C. Sandberg-The ' Old Granite' of the Transvaal. 



in front ; prolonged backwards into curved lateral ridges {r.^, r.^) on 

 slopes of hinder part of carapace. Anterior lateral pair (^^, l^) trans- 

 versely oval, lying in front of l.^ and h, and touching median unpaired 

 boss (tWj) and outermost posterior pair {l^). Median anterior unpaired 

 boss {m^) small, subrhomboidal. Outermost posterior bosses [l^, l^) 

 largest of all, obliquelj^ placed, oval, touching in front the lateral 

 bosses l^ and l^, and the curved lateral ridges above, surrounded by 

 rather strongly marked furrow. 



Posterior part of carapace divided in half by narrow median dorsal 

 ridge (r-^) running forwards from posterior margin to middle of carapace, 

 then bifurcating so as to enclose a triangular space (cardiac region) 

 between its branches (ro, Vo) and the cervical furrow, against which 

 they end. Cardiac region triangular, occupied by a large rhomboidal 

 posterior median boss (m^) and a smaller anterior triangular boss (w^g), 

 the latter flanked by a pair of subrhomboidal lateral bosses {l-^, (5). 

 Lateral ridges (^3, r^) proceeding from outer posterior bosses (/j, l^), 

 curved, narrow, rounded, thinning and dying out at about two-thirds 

 the length of the carapace without meeting dorsal ridge (r^). Surface 

 of carapace coarsely granular, with minute scattered puncta on lateral 

 slopes, which become rather larger and more numerous near the 

 marginal groove. 



Length . . . 5*50 mm. 



Width . . . 4-75 ,, 



Height . . . 2 50 ,, 

 Affinities. — This species shows points of resemblance to several 

 British forms already described. The bosses on the cardiac region and 

 bifurcation of the dorsal ridge resemble C. Harhnessi, Woodw.,^ but 

 the posterior and lateral parts of the carapace are quite different. In 

 the dorsal ridge, lateral ridges, smooth sides, and border we are 

 reminded of C. Wrighti, Woodw.,- but the bosses on the anterior and 

 cardiac portions are differently developed. C. hilohatus, Woodw., ^ is 

 less closely allied. In C. Scotti, Woodw.,* the lateral ridges join 

 the dorsal ridge behind, and the carapace is emarginate, but the 

 ornamentation seems similar. The Irish species C. Jonesianus, Woodw.,^ 

 may also be compared. 



V. — The Age of the ' Old or Grey Granite * of the Transvaal 



AND Orange River Colony. 



By Dr. C. G. S. Sandberg. 



IT may be taken for granted that everybody agrees with Dr.Molengraaff 

 when, in discussing Dr. Hatch's paper on " The Oldest Sedimentary 

 Rocks of the Transvaal," he says: ^ "There must exist, or have existed, 



1 Woodward, Geol. Mag., 1870, Dec. I, Vol.VII, p. 556, PI. XXIII, Figs. 6, 6a. 



2 Ibid., p. 555, PL XXIII, Figs. 5, 5a. 

 » Ibid., p. 554, PI. XXIII, Figs. 3, 3a. 



♦ Ibid., 1893, Dec. Ill, Vol. X, p. 28, woodcuts A and B ; 1894, Dec. IV, 

 Vol. I, p. 536. 



« Ibid., 1870, Dec. I, Vol. VII, p. 557, Text-figures 1, 2 on p. 558; 1894, 

 Dec. IV, Vol. I, p. 535, PI. XV, Figs, la, lb. 



' G. A. F. Molengraaff : Proc. Geol. Soc. S. Africa, to accompany yoI. vii of the 

 Transactions, p. xxix. 



