FOSSIL FAUNA. 103 



PLATE XLII. 



The Fossils represented in this Plate are chiefly Zoophytes in Flint. 



Fig. 1. A flint from the gravel-pits at Hackney. Its form is derived from the enclosed 

 zoophyte, part of whose structure is exposed in the upper portion of the figure. 

 This fossil zoophyte {Choanites Konigi, of Mantell) is very abundant in some of the 

 chalk strata, and many of the most beautifully marked pebbles cut and polished for 

 brooches by the lapidaries of Brighton, Bognor, and the Isle of Wight, are the 

 silicified soft parts of this animal. The original was of a subglobular form, and 

 probably of a soft fleshy consistence ; it had a deep central cavity, whence numerous 

 tubes diverged, and ramified throughout the mass ; it was fixed at the base by radicle 

 or root-like processes.' 



Fig. 2. This is another characteristic and abundant fossil zoophyte of the chalk and flint. 

 The specimen figured is a water-worn pebble, and therefore gives but obscure 

 indications of the form and structure of the original. The fungiform flints— called 

 in Sussex petrified mushrooms — belong to the same genus ( Ventriculites, of Mantell) : 

 and highly interesting specimens occur in wliich some part of the zoophyte 

 is invested with flint, and the other part expanded in the chalk. The original was 

 probably a polyparium — that is, the skeleton or support of an aggregation of coral- 

 polypes — of a funnel shape, the polype-sheUs being situated on the inner surface : 

 the base was attached by root-like fibres.^ The polype-cells are cylindrical and 

 regular, and clusters of beautiful casts of them often occur on flints. 



Fig. 3. This specimen is described by Mr. Parkinson as "a pear-shaped alcyonite from 

 Switzerland." It is probably one of those fossil zoophytes allied to the sponges 

 (called Siplionia), in which the upper part is of a bulbous or pear-like form, and 

 is supported by a stem with root-like processes at the base. The bulb has a central 

 cavity studded with irregular pores, that communicates with the parallel longitudinal 

 tubes of which the stem is composed : a structure admitting of that ready ingress 

 and egress of the sea-water, which this class of organisms requires. There are 

 numerous species in the greensand of the chalk formation.^ 



' See Medals of Creation, p. 264. " Thoughts on a Pebble," (eighth edition,) contains coloured figures and a full 

 description of these fossils. 



2 Consult Medals of Creation, pp. 270—279 : and Wonders of Geology, sixth edition, p. 638. 

 ' Medals of Creation, p. 258, Lign. 56. 



