The Invertebrate Fauna of the Uitenhage Series. 75 



of ribs directed away from a dividing line, so clear a feature in the 

 figure, is quite erroneous. In the specimen itself, an appearance of 

 dichotomy occurs only in one rib, and this seems to be due to an 

 accident of preservation. There is a crack in the shell, and a 

 portion of the valve on one side has become pushed slightly over 

 the surface on the other side of the crack. From an examination of 

 the specimen it is difficult to say with certainty whether this injury 

 took place during the life of the animal, or subsequently, but the 

 resulting irregularity in the sculpture was in any case not a normal 

 character. 



There is a close general resemblance between L. (Mantellum) 

 neglecta and L. parallela J. de C. Sow. ; :;c but in Lima ncglecta 

 the oblique elongation is greater and the posterior ribs are more 

 crowded and delicate. Lima (Mantellum) gaultina Woods t is more 

 closely similar to L. neglecta in outline, but its antero-ventral border 

 is more narrowed, and the fine linear rib in the interspace between 

 the main ribs is lacking. 



GENUS PEENA J. G. Bruguiere. 

 PERNA ATHERSTONI Sharpe. 

 Plate II., fig. 9. 



1856. Perna atherstoni D. Sharpe, Trans. Geol. Soc. Lond., ser. 2, 

 vol. vii., p. 193, pi. xxii., figs. 4, 4a. 



Occurrence. This shell was found at Dunbrodie (Sunday's Eiver), 

 in the cliff below the old school-house (282, 305, 320), and at 

 Walton's Farm, below Dunbrodie (311). It was recorded by Sharpe 

 from the same place (Geelhoutboom) " in greenish grit with 

 fragmentary shells." 



Remarks. These specimens from Dunbrodie were thought to 

 represent very probably a new form, but a comparison with Sharpe's 

 original specimens of P. atherstoni shows that they differ from these 

 in no essential particular. One of the Dunbrodie individuals, it is 

 true, shows a slight difference in outline ; its antero-inferior border, 

 at a distance of 15 mm. from the umbonal apex, has a broad in- 

 dentation or inward curve in profile, somewhat more strongly 

 developed than in the original of Sharpe's figure 4. Other specimens 

 which I have examined exhibit this feature in less degree, and it 

 appears to be a character which is subject to some individual 



* For full description and references to literature see Woods (3), vol. ii., part 1, 

 p. 28, pi. v., figs. 14, 15 (1904). 



f AVoods (3), vol. ii., part 1, p. 31, pi. v., figs. 16-20 (1904). 



