DIPOnULA VERRUCOSA. 221 



peristome thickened, especially round the upper part, 

 and bearing usually five spines, of which the lowest on 

 each side is larger than the rest ; a minute pore a little 

 below the inferior margin, and on one side a raised avicu- 

 larium, with a produced vibraculoid mandible directed 

 outwards. Ooecia globose, finely punctured. 



Locality. Lantivet Bay, Cornwall (C. W. P.). 



Geographical Distribution. Naples,, 40 f ms. (Waters). 

 Range in Time, Sicilian Pliocene (Waters). 



Nothing is known of the size which this species attains, 

 or of its mode of growth ; but the fragment obtained by 

 Mr. Peach shows it to be of a stout habit. 



The characters of the cells can best be recognized in 

 those which are placed at the tips of the branches. There 

 they are distinct, though only moderately convex, broadly 

 ovate, almost smooth, and bordered by a row of rather 

 large foramina. The surface is also usually more or less 

 covered with smaller punctures or " pit-like depressions."' 

 The pore is placed centrally at a very short distance below 

 the inferior margin. The avicularium is developed indiffe- 

 rently on either side ; it occupies the inner aspect of a 

 large conical elevation, which rises a little below the aper- 

 ture. The mandible is triangular below, and runs out 

 above into a long spinous process, similar to that which 

 occurs on Micro23orella ciliata. 



There is a little variation in the shape of the orifice ; 

 the sides are sometimes rather straighter than is usual, 

 and the constriction below is not quite so strongly marked. 

 In such cases there is less disproportion between the 

 breadth above and below. In the typical form the orifice 

 expands above, and is decidedly contracted by two lateral 

 projections a little above the lower margin, where the 

 width is only about half as great as at the top. 



