FOEAMINIFEEA OF THE KEEIMBA ARCHIPELAGO. 649 



The shell is coarsely punctate in the spaces between the verriculations of the 

 surface. 



Bolivina simpsoni exhibits great diversity of size, development, and external 

 decoration : two well-marked forms occur usually in company, one showing the 

 prominent terminal and marginal spines, the other being spineless. This does not 

 appear to be due to excessive shell-growth in the spinous form, as the sutural lines of 

 the spineless form are often even more strongly limbate than in the spinous type. 

 A short and a long type also occur, apparently definite forms, and not stages of growth ; 

 the short type is more commonly spineless, but sometimes the spines on this type are 

 quite abnormally developed. In the long type of both forms there is usually a sudden 

 change in the surface-appearance of the shell at about its mid-growth, the chambers 

 suddenly increasing in breadth and turgidity, with a consequent diminution of the 

 effect produced by the limbate sutures, thus giving an appearance of neatness and 

 hnish to the later half of the test. 



At Stn. 6 a specimen was observed in which, at this change of growth, the test took on 

 a bigenerine habit, two or three chambers having been formed in a continuous series. 



Young individuals bear some resemblance to Textularia jugosa Brady (= Textularia 

 iiiconspicua, ys-x. jugosa Millett), but are readily distinguisliable by their aperture and 

 their much greater size. 



We have found our species in the Brady Collection at Cambridge, where it figures 

 as Textularia jugosa Brady, from Tamatave .(Madagascar) shore-sand. There are two 

 slides of T. jugosa in the Collection, the other one containing typical T. jugosa from 

 Raine Island. The Madagascar spe<;imens are representative of the Kerimba form, 

 but in a somewhat pauperate condition, similar indeed to the specimens whicli we 

 have ourselves found from Ngoney (Madagascar), None of them attains the robust 

 dimensions of the best Kerimba types, and, although the limbation and verriculate 

 surface-markings are well shown in some of the stronger individuals, none of them 

 presents marginal spines. The aperture in all cases is typically bolivine. 



The species reaches its best development as regards size and numbers at Stns. 4, 9, 

 10, and 12. At Stn. 4 both -the spinous and the spineless forms occur equally large. 

 At Stn. 9 there are only a few spineless, mostly of the short type, but the spinous 

 form is very common and very large. At Stn. 10 only the spinous form was 

 observed and was very common. At Stn. 12 the short spineless and very large 

 spinous specimens were found. At Stn. 11 the spineless form only is recorded, 

 characterized by inordinately thick limbation, and coarse verrioulate markings on the 

 later chambers. 



"We take pleasure in associating this very handsome species with the nam« of 

 Dr. J. J. Simpson, by whom this material was dredged in the Kerimba Archipelago. 



Length extremely variable — a series measured ranged from "2 to I'O mm. in length. 

 Breadth less variable, between -2 and -4 mm. 



4t 2 



