40 



Of one variety of the torose, or knobbed sudes, a fragment is repre- 

 sented Plate IV. Fig. 5 ; and now take a view of Vol. I. Plate VL 

 Fig. 29, where you will have one instance of the strange, and even 

 absurd errors, to which we are liable in these pursuits. A specimen, 

 not indeed so well defined, is there given as part of the branch of a tree. 

 To mistake the spine of an echinus for the branch of a tree, you may 

 say, is pretty well; but this is trifling I will now confess to you, that 

 in the same plate, we both narrowly escaped the misfortune of having 

 part of the tusk of an elephant introduced as part of the stem of a tree. 

 I mention these circumstances, to impress on your mind the great chance 

 of error in these pursuits, from the obscurity of specimens and the simi- 

 larity of appearances, in even most different bodies. But to return : 

 The fossil just mentioned, Plate IV. Fig. 5, is a very curious variety of 

 this species, torosa, from Giengen, in Swabia, being the compressed ser- 

 rated spine which is mentioned and figured by Andrea and Leske. At 

 its inferior termination, part of its articulating head is yet to be seen. 

 Thence it assumes a compressed triquetral form, beset both on its edges 

 and faces with denticulated noduli. This is the Bacolo di santa Paulo of 

 Scilla, Tab. xxiv. Fig. 2. Representations of fragments of knobbed 

 spines are given in most writers on this subject. 



No fossil specimen of the genus Sudes fortalitiorum, pallisadoes, has, I 

 believe, been yet known : I shall, therefore, be under the necessity of 

 offering my observations on such fossils more at large, than the space, 

 to which I find myself limited, has allowed rne to treat of the former 

 species. 



The genus Sudes fortalitiorum, pallisadoes, is divided by Klein into 

 two species, the plain and the variegated with bands. For an instance 

 of the former, he refers us to Rumphius, Tab. xiu. D. D. D. ; and, of the 

 latter, he gives figures of twenty-two varieties, de Aculeis echinorum, 

 Tab. xxxiv. Of the spines of this genus, he observes, the substance of 

 which they are formed is very different from that of which the spines of 

 all the other genera are composed. Whilst all those belonging to the 



