NOTES ON RETICULARIAN RHIZOPODA. 25 



these could have been chosen for chemical investigation, for 

 the one represents a very sandy non-labyrinthic type, usually 

 but little coloured, the other a finely cemented form with 

 smooth exterior, having its chamber-cavities filled with can- 

 cellated shelly growths of deep brown colour. Both species 

 are of considerable size, and about a gramme by weight of 

 each was with some little trouble collected for analysis. I 

 have had the advantage of the assistance of my friend Mr. 

 J, T. Dunn, B. Sc, Demonstrator in the Chemical Laboratory 

 of the College of Physical Science in Newcastle, in this por- 

 tion of my work. 



The specimens were thoroughly washed, in the first place, 

 to free them from soluble saline matter, after which the 

 analysis of Hyperammina elongata, gave the following 

 result : 



Loss on ignition (organic matter and COo) . 2*9 



Silica ........ 92'5 



Peroxide of iron with a little alumina . . 2-0 



Lime and magnesia ..... 2*2 



99-6 



Treated in the same Avay the tests of Cyclammina can- 

 cellata yielded as follows : 



Loss on ignition (organic matter and COj) . 7'4 



Silica 80-5 



Peroxide of iron with a little alumina . . 8'9 



Lime 2-9 



99-7 



Perhaps the most noteworthy fact conveyed by these 

 figures is the large proportion of ferric oxide the tests of 

 both species, but especially of Cyclammina, contain. The 

 iron is present as peroxide, not as silicate or phosphate, and 

 the red colour of the shells is retained or even brightened 

 after ignition. Hyperammina gave no phosphoric reaction 

 whatever, and in Cyclammina the trace of phosphates was 

 inappreciable. It has been a matter of debate what the red- 

 brown tint of the tests of the arenaceous E-hizopoda is 

 determined by, but so far as these two species are concerned 

 there can be no longer any doubt. At the same time it must 

 not be regarded as proved that iron invariably furnishes the 

 colouring matter of the investment of Foraminifera. I am 

 at present inclined to believe with Dr. Wallich that, in some 

 thin-shelled, calcareous and chitinous forms at least, the 

 brown stain is of organic origin. 



