CHOANITES KONIGI. 235 
the shingle on the sea-shore at Bognor, Worthing, and other. 
places, very fine examples may be collected. 
_ Lign. 75, fig. 4, represents the usual appearance of a flint 
deriving its form from a Choanite; jig. 2, is the upper part 
of a Choanite preserved in chalk, and richly coloured by 
‘iron; the opening at the summit, a, is the orifice of the 
central cylindrical cavity, which is in this instance filled up 
by chalk, but in flint specimens, with silex of a different 
colour to that of the surrounding mass. If jig. 2, were 
placed on the top of jig. 4, the general shape of the original 
_ zoophyte would be represented. The opening at the base 
of fig. 4, marks the spot whence the processes of attachment 
proceeded. The vertical section of a flint, similar to jig. 4, 
is shown at fig. 3; and in this example are seen the central 
"cavity, and a section of the substance of the zoophyte, which 
is traversed by numerous tubes,. that ramify through the 
mass of which the body was composed, and terminate in 
_ openings on the inner wall of the central cavity, or sac. A 
transverse section of a similar flint is delineated in jig. 1;. the 
central white spot indicates the sac filled with flint, ad the 
tubes are seen radiating from it through the mass; under a 
_ powerful lens the interstitial structure appears to be granular 
rather than porous. The perfect transparency of the body 
_ when silicified, and the rich tints it has acquired from me- 
~ tallic solutions, and the compressed state in which it is often 
found, seem to indicate that the original mass was a soft 
" gelatinous substance, like that of the Actinia, strengthened 
by spicula; for numerous tri-radiate spines, like those on 
the left-hand of jig. 5, Lign. 75, occur occasionally in chalk 
_ Specimens. 
In many Choanites, which differ in no other respect from 
_ the present species, vertical sections show on each side the 
& figured i in my “ Thoughts on a Pebble,” Eighth Edition, pl.ii. See 
a coloured figures of Choanites in Pict. Atlas, pl. xlii. fig. 1, 9, and 10; 
pil. xliv. “ 8; and pl. xlvy. fig. 10. 
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