FORAMINIFEEA OF THE ATLANTIC OCEAN. 3 



Isles and in the North Sea area the material of which is now being 

 published by Heron-AUcn and Earland gives a great deal of new 

 information for an area worked over previously in a more or less 

 incomplete way. 



From all these records and especially from the work of Heron- 

 AUen and Earland it is at once clear that there are two general groups 

 of species of f oraminif era . those of general distribution and others of 

 very local distribution. The species, such as Psarnmosphaera how- 

 manni and P. vustica, Teclinltella thompsoni, and others are very 

 unique and seem to be rather limited in their distribution. Others, 

 like Proteonina micacea, Gh^anellafrigida, and Hyperammina distorta 

 are limited also on this side, although this may be due to lack of ma- 

 terial connecting the two areas. 



Tlie isolation of certain species in Moray Firth at very limited 

 stations seems to show that the species of foraminifera or at least 

 many of them arc not ujiiversally distributed. 



SELECTIVE POWERS OF THE FORAMINIFERA. 



Witii tlie Astrorhizidae and to a certain extent with the following 

 family, Lituolidae, the material of the test is to a greater or less 

 extent made of foreign material taken from the ocean Ijottom on 

 which it hves and cemented into a test. When it is considered that 

 this is brought about by a single-celled organism without organs or 

 specially developed sense cells of any sort it is very interesting that 

 a deiinite selection takes place in the mixed material on which the 

 animal lives on the ocean bottom, Tliat this simple protoplasmic 

 bit has a definite power of selection in the material of its test is very 

 startling. Whether it is a reaction due to chemical stimulation or 

 to tactile reactions in the case of spicules does not seem to be known. 

 As fixed species have accumulated considerable amounts of spicules 

 or other deiinite fragments it would seem in most cases as though 

 they must have moved about freely and accumulated this material 

 in the protoplasmic l)ody before the test was made. 



As of general interest and as the series of selections is subject to a 

 definite gradation it is given here at some length. 



Cement. 



CTiitinous. — In HMzainmina mdivisa there is a basal chitinous 

 layer to which the various foreign particles are attached and thelinmg 

 is separate from them, persisting even when the surface material is 

 rubbed away. A similar base is found in Pelosina and other genera. 



Ferruginous. — In the majority of the genera of these two families 

 there is a yellowish or reddisli-brown cement which may be used 

 sparingly to cement tog<3ther the sand grains of tlie t«st, as in Bhah- 

 (lamiiihm, or to make the mass of the test in which the sand grain 



