rORAMINIFERA OF THE KERIMBA AECHIPELAGO. 651 



the locality than M. affinis. The specimens do not present any particular features 

 of interest, both the spinous and the straight-edged types figured by Millett 

 occurring at most of the Stns. If anything, the spinous variety (Millett, hg. 13) is 

 the most abundant ; the surface of the test is, in its best development, much more 

 strongly marked than is indicated in the original figures, the shell-wall being ridged 

 with fine rounded costaa in the grooves, between which the typical vesicles are placed. 

 The whole of the surface of the test, especially in its initial portion, is often covered 

 with a dense outgrowth of spiny processes masking the sutural lines. The shell-wall 

 is described by Millett as " cellular or spongy," but, viewed as a transparent 

 object under a high power, this characteristic shell-wall of the Mimosinse appears to 

 be due to small vesicles in the thickness of the shell-substance communicating with 

 the interior and exterior surfaces by the pseudopodial perforations. 



M. spinwlosa appears to be more widely distributed than the other species, as we 

 have records of its occurrence at many localities in the Indo-Pacific area. 



232. Mimosiiia ecMnata, sp. n. (PL L. figs. 12-18.) 



Mimosina hystrix Millett, var., Sidebottom, 1904, etc., RFD. 1905, p. 16, pi. iii. fig. 9. 

 „ Sidebottom, 1910, RFBP. p. 13. 



2 Stations. 



At Stn. IX a few specimens were found, and a single individual at Stn. 10, 

 which are, we think, beyond question the same as those figured and described by 

 Sidebottom as a variety of M. hystrioc Millett, but, as he points out, they present 

 points of difference from that species and it appears desirable to separate them. 

 The Kerimba specimens, like those from Delos, are triserial in the eaily stages. This 

 triserial portion varies considerably in its development, in some cases extending up 

 to the terminal pair of chambers, which are always biserially arranged ; in other 

 specimens the triserial portion is very small and the shell is biserial throughout the 

 great part of its development. These two variations cause a considerable difference in 

 the external appearance of the specimens, the biserial form being much narrower and 

 more compressed than the triserial, which is turgid and practically diamond-shaped in 

 section. The whole surface of the test, except the terminal pair of chambers, is 

 covered with a dense growth of tine spines. The double aperture characteristic of 

 Mimosina is well shown in our specimens. 



Maximum breadth ■10-T4 mm., length T4-T6 mm. 



233. Mimosina hystrix Millett. (PL L. fig. 19.) 



Mimosina hystrix Millett, 1898, etc., FM. 1900, p. 549, pi. iv. fig. 14. 

 2 Stations. 



This species is represented by a- single specimen at Stn. \ B, and a few less typical 

 at Stn. "IX. At Stn. I B it is small and fairly typical, but the marginal spines are, 



