The Invertebrate Fauna of the Uitenhage Series. 63 



and Graaff-Eeinet (345-349). These occur in a hard limestone 

 matrix, and the coral itself is replaced by crystalline carbonate of 

 lime and is in a condition unfavourable for detailed study. The 

 corallum is relatively slender, subcylindrical and branching in form. 

 The calicinal centres are situated at about 2 mm. from one 

 another. 



Prof. J. W. Gregory has seen a specimen of this form, and con- 

 siders that it may be correctly assigned to the genus Thamnastr&a. 

 In view of the scanty material so far obtained, and its imperfect con- 

 dition, a fuller description and comparison with described species 

 may be deferred for the present. 



CLASS ANNELIDA. 



GENUS SEEPULA Linnams. 



SERPULA cf. CONCAVA (J. Sowerby). 



Plate II., figs. 1, la. 



Cf. 1814. Vermicularia concava J. Sowerby, The Mineral Conchology 



of Great Britain, vol. i., p. 125, Tab. 57, figs. 1-5. 

 ,, 1836. Vermetus concavus J. de C. Sowerby, Trans. Geol. Soc. 



Lond., ser. 2, vol. iv., p. 343, pi. xviii., fig. 10. 

 ,, 1884. Vermicularia concava E. Damon, Geology of Weymouth, 



Portland and Coast of Dorsetshire, 2nd edition, p. 128, 



fig. 48. 



Description. The tube is wound in the form of a very flat spire, 

 widely umbilicated, with the apical part not projecting above the 

 outside whorl when viewed in lateral profile. The whorls are in 

 close contact, or slightly embracing. The tube is of slightly flat- 

 tened cylindrical or oval section, the flattening at right angles to 

 the axis of the spire. After the third whorl the tube ceases to be 

 coiled and becomes free. The surface of the tube is marked by 

 numerous irregular transverse wrinkles and furrows. 



Dimensions. 



Greatest diameter across the whorls 9 mm. 



Greatest external diameter of the tube at the close 



of the coiled stage 3 ,, 



Occurrence. A single specimen was found between milestones 



