386 Mr. H. J. Carter on the " Tubulations Sableuses " 



of the disintegrated grains mixed up with isolated fossil 

 sponge-spicules in a beautiful state of preservation, which 

 cover it, as will be seen hereafter, can be shaken out of the 

 " tubulation," leaving its mould only between the cylinder 

 and the concretionary crust of sand outside (fig. 2,b bb). It is 

 therefore to this mould or impression of the pisiform sui-face 

 left in the inner side of the concretionary crust that we must 

 chiefly look for the exact form of the pisiform surface of the 

 tuberculous layer ; and here we shall find a cancellated appear- 

 ance that, in the form and dimensions of its scale-like divi- 

 sions, where most symmetrical or perfect^ indicates a surface 

 exactly like that on the central cylinder already described 

 (fig. 4, f\ and fig. 5, a), only that the grooves between the 

 pisiform tubercles are much deeper, and therefore the con- 

 vexities of these eminences (that is, of the interspaces) much 

 more prominent, so as, indeed, to present the general tuber- 

 cular pisiform character mentioned (figs. 6, 7, and 8). Thus 

 the average distance, perhaps, between the summit of the 

 pisiform eminences and surface of the cylinder is about a 

 centimetre (fig. 2,/) ; and this gives the thickness of the tuber- 

 culous layer, which varies very much according to locality and 

 circumstances, being least in thickness pesteriorly or round the 

 pointed end (?tail) of the cylinder ; while the grooves between 

 these eminences in many cases reach down nearly to the central 

 cylinder, with which, as before stated, they are in direct contact 

 (figs. 7 and 8) ; and in one specimen that I have, some of the 

 lateral eminences are conical, one centimetre long, and project 

 outwards on both sides at right angles to the compressed 

 cylinder (fig. 2,/), still further giving it the appearance of an 

 Annelid ; while another specimen of the " compressed" cylin- 

 der presents a lobate or segmented appearance (fig. 3). 



Concretionary crust. — Nothing more need be stated of this 

 than that it is derived from the deposit in which the " tubula- 

 tions " are imbedded, and, although causing the latter to 

 assume different forms outside^ in no way indicates the condi- 

 tion of the interior (fig. 2, a a, &c.) ; hence the necessity of 

 breaking open this crust or case cautiously before tlie form 

 presented by the fossil itself can be seen and described. M. 

 Vanden Broeck states that he has found specimens of the 

 '' tubulations sableuses " one metre in length, and that some 

 are pyriform, of which I have fragments of the outer case 

 only; but as the tuberculous layer and the concretionary 

 crust are by no means certain indications of the form of 

 the central cylinder, which may be either circular or oval, 

 it would be advisable to ascertain if the latter is in size and 

 shape like one of these — that is, not pyriform. As to length, 



