FORAMINIFEEA OF THE KEEIMBA AECHIPELAGO. 699 



The figure of I), rhnosa is not in strict agreement with the verbal description. It 

 represents a very finely perforated shell with apparently smooth and hyaline surface^ 

 The secondary chambers on the under side are well shown, but the aperture is very 

 obscure. The chinks between the later chambers on the superior surface are very 

 marked. 



The figure of D. j}oh/sfomelIoules represents an extremely coarse and granulose- 

 surfaced shell. The secondary chambers are barely suggested. There is a single 

 distinctive aperture on the umbilical margin of the last chamber on the inferior side, 

 but the figure does not demonstrate whether this aperture belongs to the primary or 

 to the secondary series of chambers. The chinks are bridged by two or three retral 

 processes which join the successive chambers. 



Brady, while adding nothing to the verbal analysis of the species, published 

 excellent figures of a type practically intermediate between Parker and Jones's figui'es 

 of J), rimosa and B. polystoineUoides. The early chambers are coarsely granulose, the 

 later ones being comparatively smooth but coarsely perforate. The retral processes 

 are prominent and numerous, and more or less obscure the chinks between the 

 chambers. The secondary chambers are well shown, and there is a single large 

 comma-shaped aperture ])lace(l on the inferior side of the shell at the innhilical edge of 

 the last chamber of the secondary series. No opening into the large chambers of the 

 primary or superior series is shown. 



I), polystomelloides occurs at nearly every Stn., but, as a rule, very sparingly. At 

 Stns. 6, 9, 10, and 12, however, the species is fairly plentiful in the coarse material 

 and the specimens are especially large and finely developed. As a whole, the Kerimba 

 specimens are of the Brady type of shell, the granulose surface being practically 

 confined to the earlier chambers. At Stns. 9 and 12 this absence of granulation is 

 especially marked. The specimens, although large and coarsely perforate, are smooth 

 and comparatively thin-shelled, with the result that the internal structure can be 

 clearly followed when specimens are examined in balsam. 



This structure appears to be much more complicated than in the other asterigerine 

 species of Biscorhina, each series of chambers having a special and definite aperture. 

 Whereas, however, in other asterigerine Discorbinse the secondary chambers are 

 situated on the inferior surface of the test, in D. polystomelloides they appear to be 

 almost entirely enclosed in the test, owing to the production of the superior or primary 

 chambers into processes which extend to the umbilical region on the inferior side of 

 the test. Here is situated the general aperture, which is of the usual discorbine or 

 " comma "-shape. This aperture is well shown in Brady's figure c, but is there 

 attributed to the inferior or asterigerine series of chambers. 



The asterigerine or secondary chambers are narroAv and long. Radiating from the 

 umbilicus nearly to the peripheral margin, they lie immediately under the " chinks " 

 which separate the large superior chambers. These "chinks" open directly down 



