POEAMINIFEEA OF THE KEEIMBA ARCHIPELAGO. 371 



world. Some northern forms are now recorded for the first time from Tropical Seas, 

 while quite a number of species hitherto known only from the East Indian and Malay- 

 Seas are typical of the Kerimba dredgings. 



The occurrence of a limited number of species usually regarded as inhabitants of 

 brackish water is doubtless due to the numerous wadys and rivers on the coast.- The 

 specimens have probably been washed out to sea by floods from coastal marshes and 

 lagoons. Many of the dredgings contain seeds and insect-remains due to the same 

 causes. 



The Kerimba material has, moreover, enabled us to work out the affinities of certain 

 organisms which had been known to us for many years, but which we had hitherto 

 been unable to assign to their proper position owing to the scarcity of the specimens. 

 We have established two new genera for their reception, and we take the opportunity 

 afforded by this introductory paper to describe and figure them in the detail which 

 seems called for by their zoological significance. 



On Iridia and Noukia, Two new Genera of Arenaceous Foraminifera. 



Family Astkorhizid^. 

 Iridia, gen. n. 

 Iridia diaphana, sp. n. (PL XXXVI.) 



Thurammina papillata (?) ; Earland, 1905, FBS. p. 201, pi. xi. figs. 6, 7 ; pi. xiv. figs. 1-3; 



Heron-Allen and Earland, 1908, etc. SB. 1909, p. 3.23. 

 Webbina hemisphcerica (?) ; Herou-Alien and Earland, 1908, etc. SB. 1909, p. 325, pi. xv. 



fig. 14. 



Test adventitious, usually attached, but occasionally more or less free, consisting of a 

 single cavity lined with a chitinous and diaphanous membrane or pellicle. The animal 

 commences its existence as a small hemispherical dome-shaped chamber, white or . 

 light grey in colour (PI. XXXVI. figs. 1, 2) attached to sand-grains or shell-fragments, 

 and constructed of very fine particles of mud and sand cemented together into a rather 

 friable test with a chitinous lining. This chitinous lining is usually continued as a 

 "floor" to the dome-shaped chamber (figs. 4, 5, etc.), but in the youngest stage the 

 chitinous " floor " is perhaps not always present. This early dome-stage is sometimes 

 furnished with an aperture at the side or top of the dome (fig. 3), but quite as often no 

 special aperture is visible. The test increases in size by the protrusion of the proto- 

 plasm in irregular masses, which proceed to secrete a covering investment of sand- 

 grains of varying sizes, attached to the chitinous lining. The construction of the test 

 becomes coarser with the growth of the organism, and the colour becomes darker 

 (fig. 11). With each increase in the size of the test, the enclosing wall of the preceding 

 stage is absorbed so as to leave an undivided cavity, the shape of which varies according 



VOL. XX. — part XII. No. 2. — November, 1914. 3 a 



