16 
species, serving to model the increasing shell, or to perform some 
other important service ; are questions which must be answered by 
some future investigator. 
The genus C. assulata, of Klein, is undoubtedly unfounded, since 
the distinction, which is derived from a distinct view of the assulae, 
or plates, composing the shell, and of the sutures by which these are 
connected, depending merely on the thickness with which the tuber- 
cula are disposed, and on the bowldered state of the shell, cannot be 
regarded as even a specific distinction. 
Of the several species placed by Klein under this assumed genus, 
none have been noticed as fossils, except C. Sardiaca Klein, Tab. ix. 
a. b. by Scilla, Tab. xvi. Fig. 1, and Tab. xxvi. Fig. b.; C. Botryoides, 
Klein, Tab. xi. h. by Aldrovandus, Mus. Metal, p. 457 ; and C. 
Toreumatica, Klein. Tab. x. n. e. by Leske, Tab. xliy. Fig. 2. 
I cannot introduce the necessary notice of the Echinites favagineus 
in any better place, I presume, than this. The echinitce thus named 
bear on their surfaces hexagonal cavities, which give to the fossil 
somewhat of the appearance of a honeycomb. These fossils have been 
noticed by Encelius, Wormius, Olearius, Oliger, Jacobfeus, and others ; 
but without any rational conjecture having been offered as to their 
nature and origin, until the attention of M. Walch was attracted by a 
very beautiful specimen, and his ingenuity was exercised in its exami- 
nation, Monumens des Catastrophes, Tome II. Sect. 1 , p. 155. This 
fossil he describes as a crystallised cast of an echinite, composed of 
hexagonal cells, resembling those formed by the bee. These cells, 
he observes, agree exactly in their margins with the shape of the 
plates of the echinus, with which they also agree in their general form ; 
and hence he infers, that the sutures, by which the plates were con- 
nected, had influenced the formation of these hexagonal cells. 
In answer to the inquiry, in what mode is this influence exerted, 
M. Walch remarks, that the cavity of the shell being filled by any 
crystallising fluid, the first formation of crystals would be, that which 
