PLATE % 3, 4< . 
ENTROCHIT^. CHERT AND LIMESTONE, 
FIG. 1, 2, 3, 4, 5, 6, 7, 8. 
HELMINTHOLITHUS Entrochites stipite 
articulis zequalibus ; ambitibus lasvlbus. planis, ramis 
alternis articulatls. S. p. 
A fossil worm — tlie original an Entrochus — Stipe cylin- 
drical; the joints equal ; their ambits even, and flat. The 
branches or lateral arms (in such specimens as retain them) 
alternate, slender, tapering, and jointed like the stipe. 
The most general of the Derbyshire Petrifactions. It 
occurs, more or less, throughout our Limestone ; but par- 
ticularly near Monyash and Bakeivell, where the strata 
appear, in some places, almost wholly composed of frag- 
ments of this and other Entrochitre 
* These bodies exhibit a great variety of forms — But the species are not 
so numerous as a casual observer would suppose. The structure of the 
Entrochus is complicated when compared with that of shells and other 
txwuia : and hence, the petrifactions of the same species differ in figure, 
according as the various parts of the original have been mCire or less perfectly 
preserved. I have endeavoured to reduce these merely accidental varieties 
into some order — perhaps this might have been done with greater accuracy, 
had I been more successful in my search after entire specimens ; but it is 
particularly worthy of notice, that notwithstanding the prodigious quantity 
of the stems found in this equnty, the head or body of the animal has very 
rarely been met with. 
