176 DR. THOMAS ALCOCK ON QUESTIONS REGARDING 



of this material soon became evident^ and it is sufficient to 

 say that daily examinations of it from that time to the 

 present have not yet exhausted its novelties. Since I 

 obtained the first sample, Mr. Glover has favoured me at 

 various times with further supplies from this place and 

 from neighbouring localities ; Mr. Darbishire has also fur- 

 nished me with a large stock of the Dogs Bay sand, and I 

 received from the late Mr. Parry some remarkable material 

 from the same place, obtained, however, under peculiar 

 circumstances, having been skimmed from the surface of 

 pools left by spring tides. In this case the sand of the 

 shore had become thoroughly dry by exposure to the sun 

 and air during the interval of the low tides, and when 

 again covered by water, the lighter and more perfect of the 

 Poraminifera floated on the surface, while broken specimens 

 and the heavier kinds sank, so that in this way a selection 

 was made natm'ally, like that resulting from the plan re- 

 commended by Prof. Williamson for obtaining specimens 

 from samples of sand which are too poor to be worth ex- 

 amination in the ordinary way. 



This naturally selected sample has furnished some very 

 interesting results, by supplying great abundance of speci- 

 mens of certain varieties comparatively rare in the rough 

 sand ; but at present I have seen in it only two marked 

 forms which have not been met with in the other samples; 

 these are two varieties of Lagena, namely, Lagena crenata, 

 described and figured by Messrs. Parker and Jones in the 

 ' Transactions of the Royal Society ' as from Swan River, 

 Australia, but not hitherto recorded, so far as I am aware, 

 as recent British ; and Lagena antiqua, plate IV. fig. 3, a 

 form which is very distinct in character from the other 

 varieties ; it is opaque white, and appears finely granular 

 in texture ; its surface is without any raised markings, and 

 at the base of the neck there is a projecting collar. 



My present intention, however, is not to describe varieties 



