SKETCH OF THE 



It is always exceedingly difficult to refer organic remains of this 

 class to any particular genus. I am inclined to believe, however, that 

 these form varieties of the alcyonium, and perhaps some of them ought 

 to be classed with the sponges. In many of them I could trace appear- 

 ances of a cortical covering, and in one or two instances, especially in those 

 which occur detached, I think I could discover something like a con- 

 centric laminar structure. This appearance is only observed at their sur- 

 face, and might have been occasioned by the original animal having had 

 a cortical covering— wo^/^m^g- like fibres could be perceived ; — the above cir- 

 cumstance, however, inclines me to include them in the class alcyonium. 



No. 3 — Is occasionally met with, but is not so common as either of 

 the two preceding. The accompanying sketch will give a pretty cor- 

 rect idea of the remains of this kind, both as to their size, form, and 

 mode of occurrence in the limestone. They occur, then, in the solid 

 rock, — are perfectly mineralised, and are of the same color as the 

 limestone. In specimens where this limestone has a structure in- 

 clining to granular, the remains of this kind exhibit a closer 

 and more compact texture than the surrounding matrix. They ap- 

 pear to have formed the ribs of some animal, probably of aqua- 

 tic origin. The vertebral extremity is flattened about seven-eighths of an 

 inch ill breadth, and the whole is slightly curved, and tapers to a point. 

 The pointed sternal extremity does not seem to exhibit an articulating 

 surface. It is thicker than the vertebral extremity, and a sharp spine 

 runs from the point of about two inches in length, from which spine the 

 bone had. sloped on either side. 



The only other organic remain which I have observed, is a shell; but 

 in so imperfect a state, that I cannot decidedly say under what genus it 

 ought to be included. It had obviously been a bivalved shell ; but little 



