402 Annals of the South African Museum 



divided ; crura stout, short, closely placed. Margins of valves at 

 cardinal shoulders slightly introverted. Surface of shell marked 

 with about 40 straight radiating low rounded ribs, rather closely 

 placed, the intermediate grooves being narrower. Concentric growth 

 ridges few, rarely present. 



Estimated length 40-50 mm. (The precise measurements cannot 

 be given as the specimens are all fragmentary and crushed.) 



As far as the above characters take us this shell resembles 

 B. atlantica Clarke," of the Lower Devonian of Maine, in its 

 external and internal features, but the American form has not 

 the introverted margins, and in this particular as well as in the 

 structure of the hinge-plate B. {Beachia) suessana Hall, and 

 B. (B.) anqylexa Clarke, (oj). cit., p. 248) may be compared with 

 it. The European B. strigiceps Eoemer, also appears to be closely 

 allied. 



It is almost certain that Bensselceria sp. a, previously described 

 by me,f is identical with this Montagu form. Schwarz thinks that 

 my B. sp. a is probably the same as his B. relicta,l but his descrip- 

 tion and figure are hardly suflScient for me to pass an opinion with- 

 out seeing his specimen. If it should be ultimately proved that 

 these three forms are identical, Schwarz's name, B. rclicta, must be 

 adopted. 



RENSSEL^EIA cf. CAYUGA Hall and Clarke. 



(PI. XLVIII., fig. 8.) 



One external cast of a crushed and flattened brachial valve of a 

 species of Bensselaria from Uitenhage differs from the other Bokke- 

 veld species by its numerous ribs. The shell is of a broadly elliptical 

 shape, measuring 42 mm. in length and about 34 mm. in width. 

 The surface is ornamented with 60-70 straight radiating narrow 

 rounded ribs, a very few of which bifurcate at about one-third to two- 

 thirds their length ; the interspaces are narrow and rounded, and all 

 the ribs at the margin are subequal in size. No concentric ridges 

 or striae are present. In shape as well as ribbing this imperfectly 

 known shell resembles B. cayuga Hall and Clarke, § from the 

 Oriskany Sandstone. 



* Clarke, Bull. No. 107 N.Y. State Mus., 1907, p. 243. 

 t Keed, Ann. S. Afr. Mus., vol. iv., pt. 3, 1903, p. 176, pi. xxi., fig. 8. 

 I Schwarz, op. cit., p. 364, pi. vii., fig. 7. 



§ Hall and Clarke, PalESont. New York, viii., Braeh. ii., p. 370, pi. Ixxv., 

 figs. 1, 2. 



