24 MR. F. CHAPMAN ON FORAMINIFERA 
Form B (microspheric form).—Test discoidal, outline circular ; 
in young individuals very thin, and with the surface granulate. 
The central area in young and middle-sized specimens is occupied 
by a small boss, about one-half the diameter of that in the 
megalospheric form ; after the test has attained the diameter of 
about 15 mm., this central prominence is soon levelled over, since 
at that period the animal thickens its superficial shell-layer, and 
covers over any irregularity of surface, including the papillate 
ends of the non-tubulous cones of the shell-wall. 
Diameter of test =, to 23 inches. 
In C. Carpenteri, especially in the microspheric form (B), the 
concentric rings of chamberlets are frequently incomplete owing 
to the fracture of the periphery during the growth of the animal, 
which repairs the edge at first by a series of chamberlets parallel 
with the broken edge, the length of each chamberlet being in 
succeeding annuli of increasing proportion in the parts requiring 
more material to bring the contour of the disc back again to its 
circular form. In this ability to repair the fracture, to which it 
is so liable on account of its form and thinness, it resembles Orbi- 
tolites in the porcellanous group, and especially O. tenuissima, 
Carpenter, who has already pointed out * that this phenomenon 
is commoner in the genus Cycloclypeus than in Orbitolites. 
The microsphere of a typical specimen of form B from Funafuti 
measured 140 p in diameter. 
It is difficult to obtain specimens of the full-grown micro- 
spheric form which show the central chamber intact, for in 
nearly all cases the median area, containing the sarcode, has been 
cleared away by a species of Cliona. 
Distribution around Funafuti, and in other localities in. the 
Pacifie.—The general geological and geographical distribution of 
Cycloclypeus has been already given (see anted, pp. 21, 22). 
Cycloclypeus Carpenteri has never yet occurred in the lagoon 
dredgings, although nearly all the other genera of Foraminifera 
found at Funafuti have been found irrespectively inside the 
lagoon and on the outer side of the reef. 
The depths at which Cycloclypeus has been found in the dredg- 
ings made by Messrs. Halligan and Finckh are as follows :— 
The young of both forms (A and B) from 30-200 fathoms. 
The fully-developed form of A from 30-200 fathoms. 
The fully-grown microspheric form of B from 46—200 fathoms. 
* Phil. Trans. vol. cxlvi. (1856) p. 556. 
