Locomotive and Non-locomotive Crinoidea. 57 



of Nautilus and Ammonite, and a few bivalves, chiefly Inoceramus 

 Cuvieri, are found in them, but there is no fossil common to the beds 

 separated by the last-mentioned fault. 



The beds overlying these undoubted cretaceous strata have been re- 

 ferred by the French geologists, quoted by Mr. Pratt, to the upper 

 part of the cretaceous system, both on account of the superposition 

 and direction of the strata and of the contained fossils, which they 

 regard as cretaceous species. But a closer examination of the or- 

 ganic remains shows that such as may be identified with known 

 species are mostly tertiary forms, while such as appear to be creta- 

 ceous, belong to genera and species of variable and uncertain cha- 

 racter. The Echinodermata, as identified by Dr. Grateloup, do not 

 agree with the references, except one, which is a tertiary species. 

 The variation in the mineralogical character of the beds sufficiently 

 accounts for the gradual change of species observed from the first 

 rise of the strata to their termination. Certain species were common 

 to all the beds preceding the second fault. The deposit is appa- 

 rently covered in its upper part by the plastic clay, to which it 

 approaches nearest in mineralogical character. At Dax and at 

 Royan similar deposits under similar circumstances were observed 

 by Mr. Pratt. 



On the whole, the author concludes that the characters of the 

 deposits in question are tertiary, and that they may probably be 

 placed earlier in the series than any described Eocene beds (unless 

 we except the Diablerets and some other deposits allied to them in 

 position and palseontological characters). The whole of the Biar- 

 ritz beds have apparently been elevated at a period posterior to the 

 elevation of the chalk, the elevating causes disturbing at the same 

 time the neighbouring cretaceous beds. 



March 8. — A paper was read " On the Locomotive and Non-loco- 

 motive powers of the Family Crinoidea." By J. C. Pearce, Esq., 

 F.G.S. 



The author is induced, from an examination of the various modes 

 of attachment among the Crinoidea, to separate those animals into 

 two great groups, the Non-locomotive and the Locomotive. The 

 former, when once attached to any solid substance by their base or 

 foot, were immoveably fixed ; the latter possessed the power of grasp- 

 ing with the foot any substance, and again relaxing their hold at 

 pleasure. The non-locomotive Crinoidea he subdivides into solid- 

 footed and root-footed. In the solid-footed the foot is formed like 

 an irregular cone with the base downwards, and is composed of suc- 

 cessive laminae, which envelope the inferior part of the column and 

 increase in number as the animal advances in age. This base or 

 foot is generally found firmly adhering to the rock in the fossil state, 

 although specimens are sometimes found detached which appears to 

 have been caused by violence during life. The columns of all the 

 species which Mr. Pearce has examined are very short and destitute 

 of side-arms. He enumerates Encrinites moniliformis from the Mus- 

 chelkalk, Apiocrinites rotundus from the Bradford clay, and Cyatho- 

 crinites tuber culatus from the Dudley limestone, as examples of this 



