622 MESSES. E. HERON-ALLEN AND A. EAELAND ON THE 



more eccentric in shape as they were added, the two chambers forming the final 

 annulus being lobose and amoebiform in shape ; the specimen appears to have been of 

 the most depressed type— Carter says that its thickness was almost inappreciable. He 

 refers to the absence of any visible aperture, which he inferred was inferior, but we 

 have been unable to verify the existence of a definite aperture in any portion of the 

 test. He also states that there is no particular arrangement of the spicules, " which as 

 often cross each other, as they are seen to be only one layer deep, and with reference 

 to their relative position lie in all possible directions, seldom appearing above the level 

 of the surface, although evincing by the occasional projection of one end or their 

 entire separation about some part which has been broken, the form above desci'ibed." 

 In the Kerimba specimens, however, there is a definite arrangement of the spicules as 

 regards the inferior and superior sides of the test respectively. On the superior side 

 the spicules are more or less generally arranged in definite lines following the spiral 

 curve of the shell, while on the inferior side they are nearly always arranged radially 

 from the central depression to the edge of each chamber. This arrangement of the 

 spicules is fairly well illustrated in Hollick's figure in the ' Challenger ' Report, especially 

 as regards the inferior view. There is often great variation in the size of the spicules, 

 not only in different specimens, but in different chambers of the same individual, 

 and the variation is not always as might be expected in the direction of a larger 

 spicule with an increase in the size of the chambers. In one specimen at Stn. 11 the 

 initial chambers of the shell are composed of a few spicules very much larger than 

 the average, and nearly twice the size of those forming the later chambers of the test. 

 In another specimen from the same Stn. the spicules in all the earlier chambers are 

 remarkably small, and the terminal chamber is built, so far as its inner margin is 

 concerned, of similar minute spicules, while the peripheral portion is constructed of 

 larger spicules, five or six times as large as the former. When Carterina assumes the 

 scale-like depressed form, at any rate, the final chambers are strengthened by the 

 formation of internal labyrinthic walls, and this is M'ell shown when a specimen is 

 mounted in balsam. A similar tendency to form strengthening walls between the two 

 faces of the test is exhibited in Ilaploiihragmium foliaceum Brady. 



The spicular bodies in Carter's original figure answer to his written description, 

 " round, smooth, fusiform, transparent, and solid calcareous spicules whose ends are 

 -sharp-pointed or round." Brady described them as " solid fusiform bodies with pointed 

 ends." — There is, however, much more range of form than Carter apparently had oppor- 

 tunities of observing ; the spicules in the Kerimba specimens vary from short cylinders 

 with almost squarely terminating ends, to the most acutely pointed fusiform bodies ; 

 the blunt cylindrical spicules give an appearance of regular " brick-work " to the walls 

 when they occur. Interspersed among the fusiform spicules, and varying greatly in 

 numbers, are a number of small spherical bodies. These are presumably what Carter 

 referred to when he described the spicules as interwoven and cemented together by ■' a 



