Dr. G. C. Wallicli on the CocQospliere. 349 



seen it incidentally stated that " nuclei " had been observed 

 in Gromia by Max Schultze. On turning to Dr. Carpenter's 

 ' Introd. Study Foram.' pi. iv. fig. 13, I found, as I expected, 

 the figure of a highly magnified view of a mass of sarcode, 

 containing two spherical granular masses, the explanatory 

 description being as follows : — " Nuclear bodies ? \_sic\ imbed- 

 ded in the sarcode of Gromia. After Schultze." Not having 

 Schultze's work to refer to, it is out of my power to say 

 whether these bodies represent true nuclei or merely sarcohlasts. 

 But be this as it may, if the credit of the discovery of a 

 nucleus in Gromia be due to Schultze, most cheerfully do I 

 cede it to that distinguished observer. 



EXPLANATION OF PLATE XVII. 



Fig. L Coccosphcera pelcKjica (Wall.), with its complement of coccolit/is. 



Fig. 2. Cell- wall of same, showing distinct membranous outline ; most of 

 the coccoliths having been thrown off. 



Fig. 3. Coccosphcera Carterii (Wall.). 



Fig. 4. The same in the dehiscent (?) condition. 



Fig. 5. Coccolith of C. pelagiea seen from external aspect ; showing the 

 radiate striation on margin of outer disk, and the central depres- 

 sion which constitutes the " central clear space " of Huxley. 



Fig. G. Coccolith of C. Carterii; side view, showing the two central de- 

 pressions and radiate marginal striae, together with the inner 

 disk and intermediate piece. 



Fig. 7. The same, as seen from its external aspect, this being, in short, a 

 front view of the outer disk. Here also the two button-hole-like 

 depressions are shown. 



Fig. 8. Circular coccolith of C. pelagiea occasionally met with. 



Fig. 8 fl. A specimen of a form of coccolith occasionally but rarely occur- 

 ring, in which there is no central depression, but apparently an 

 aperture close to the margin of the outer disk. 



Fig. 9 D. Diagrammatic, enlarged, side view of coccolith of C. pelagiea. 



Fig. 10 D. Diagrammatic vertical section of same, showing the central 

 depression (a), in external disk : s, the stem ; e d, the inner disk. 



Fig. 11 D. Diagrammatic fi-ont view of the outer disk of same : a, the 

 central depression, the " central clear space " of Huxley, and 

 '' nucleus " of other writers ; h, the innermost ring, indicating 

 the margin of this depression ; c, the ring indicating the outline 

 of the intermediate piece, or stem uniting the two disks ; d, the 

 ring indicating the margin of the inner disk ; e, the outline of 

 the outer disk itself. Possibly these are the rings referred to in 

 Prof. Huxley's Report of 1868, when describing the coccoliths 

 as " curious rounded bodies, to all appearance consisting of 

 several concentric layers surrounding a minute clear centre." 



Fig. 12 S. This figure is copied from fig. 20, plate 16, appended to Prof. 

 Oscar Schmidt's paper " On Coccoliths and Rhabdoliths " 

 Annals & Mag. Nat. Hist. Nov. 1872, translated by W. S. Dallas, 

 F.L.S. It is described in the text (p. 367) as " a decided 

 coccolith with a dorsal shield, as may be ascertained by placing 

 it on its edge, the dark non-gi-anular part, 6, representing the gra- 

 nular zone, and tlie clear spaces in it ; «, divided medullar space 

 tpifhouf central gnnvtlrs.'' 



