196 ilR. JUKES-EEOWJS^E AND PEOE. HAERISON 



might in every instance have been reduced with advantage, though 

 the foraminifera had already suffered considerably by breakage. 

 The small quantity of washed material thus obtained (5 to 20 or 30 

 grains from each ounce of rock) is not much to depend upon for the 

 complete presentment of the calcareous rhizopods. Neither are 

 microscopical sections of any great service, except for purposes of 

 comparison, owing to the muddy nature of the deposits and the 

 relative sparseness of recognizable organisms. 



" In three out of the eight samples to which I have referred no 

 foraminifera were met with ; in a fourth very few, and those only 

 of species common to the others.^ The results of the examination 

 of the remaining samples are embodied in the first four columns of 

 the annexed table (p. 198). 



" There was one specimen, as I have said, which differed from the 

 rest in its physical characters ; it was labelled ' rotten earth, Bissex 

 Hill, 50 feet down.' It is a light-brown friable rock which easily 

 disintegrates, leaving 40 per cent, of residue or thereabouts after 

 washing. It is more calcareous than the rest, containing perhaps 

 less than 25 per cent, of siliceous matter. It resembles in many 

 respects some recent specimens of Glohigerina-ooze. 



" There is still much to learn respecting the rhizopod fauna of 

 these deposits before any very satisfactory conclusions can be drawn 

 as to their geological age or the depth of water at which they were 

 formed. The species which have been so far determined are enume- 

 rated in the annexed table. This has no pretension to completeness, 

 but it will serve as a basis for future work ; the number of species 

 in every column might, without doubt, be largely increased by fresh 

 examination with improved methods of preparing the material. 



" The list contains 81 species and well-marked varieties, 5 of 

 which are left for the present undetermined. Of the remaining 76 

 there are only 2 species of Nodosaria and 3 of Ellipsoidina that 

 are not well known in the living condition. It may be further 

 remarked with regard to Ellipsoidina that our present knowledge of 

 the genus and its distribution is very defective ; it appears more 

 than probable that specimens belonging to the group, both recent 

 and fossil, may have been mistaken for isomorphous forms of Lagena, 

 Glandulina, and Nodosaria. The two species of Nodosaria referred 

 to are represented by only one or two specimens apiece, and taken 

 by themselves are of little importance. 



" We may say with some confidence that of the 81 species of fora- 

 minifera enumerated 71 or 72 are certainly recent forms, and half 

 the remainder probably so. An investigation of the microzoa of a 

 large series of soft deposits from various islands of the South 

 Pacific has yielded a very similar result, and I agree entirely with 

 Dr. Gruppy, who has assigned to them geologically a post-Tertiary 

 origin. 



'■ Eleven specimens had been sent to Dr. Brady, and those which proved of 

 little use must have come from some of the following locahties : — Castle Grant, 

 lower beds (3 samples sent) ; near Bloomsbury ; Mount Misery ; summit rock 

 of Mount Hillaby. 



