254 



HARD WICKE 'S SCIENCE ■ G OS SI P. 



singular little Rhizocrimis lofotensis brought up 

 from the bottom of the North Sea, in the living state, 

 by Messrs. Carpenter and Wyville Thomson, during 

 one of their earlier dredging expeditions. This 

 Rhizocrimis is one of the last survivors of a once 

 cosmopolitan race of animals, now all but extinct, 

 whose functions seem to be usurped by members of 

 the Sea-urchin family. Stems, and sometimes small 

 heads, and the joints of the arms of an Encrinite 

 nearly allied to the living Rhizocrimis, and almost as 

 small as it, are frequently found in the Chalk, and 

 especially on the surfaces of the flint nodules imbed- 

 ded in the chalk, in the neighbourhood of Norwich. 



Glyptocriniis basalis is common almost everywhere 

 in the Silurian rocks, but especially so in those of 

 Wales. At Myndd Fronfrys, about two or three 

 miles from Llangollen, large numbers of the remains 

 of this fossil may be found, as indeed may those of 

 other common Silurian Crinoids. The generic name 

 of Glyptocriniis (signifying "sculptured") is in allusion 

 to the highly ornamented basal plates of the body or 

 pelvis. Cfofalocrimis has the first part of its name de- 

 rived from a Greek word signifying a "child's rattle," 

 on account of its peculiar shape and appearance. The 

 arms commence at the top of the body, and as the joints 

 or ossicles are fastened to each other sidewise, as well 

 as vertically, the arms have a subdivision resembling 

 the meshes of a net, or the basket-work of a child's 

 penny rattle. When portions of these arms are 

 found, as they frequently are, on the surfaces of the 

 Wenlock and Dudley limestones, they look like 

 fossil Polyzoa or "Sea-mats," and are frequently mis- 

 taken by young geological students for such. Another 

 Silurian genus of Encrinites, called Anthocrimis from 

 its flower-likea ppearance, has its arms subdivided, 

 something after the fashion of those of the Cro- 

 talocrimis. 



Periechocrim/s, Rhodocrimts, Taxocrimis, and 

 Poteriocriniis are other common Silurian genera, 

 nearly always found in the various limestones of that 

 formation. Rhodocriniis, or the " Rose Encrinite," 

 ranges upwards in the Primary rocks to the Carboni- 

 ferous limestone, in which it is found in Lancashire. 

 The joints of its column may be known by the five- 

 sided hole running through the middle. On examin- 

 ing the weathered surfaces of the Silurian limestones 

 in the neighbourhood of Wenlock or Dudley, the 

 student will often find splendid, sometimes perfect, 

 specimens of one or another of the above-mentioned 

 Crinoids. Glyptocrimts appears to be most abundant 

 in the Caradoc beds, and may be found wherever 

 they are well exposed. 



In the neighbourhood of Newton Abbott, Torquay, 

 and elsewhere, where the Devonian limestones crop 

 out, remains of Encrinites peculiar to this formation 

 in tlieir specific cliaracter, may be found, although not 

 abundantly. It would seem as if corals, having 

 pretty much the same marine habits as Encrinites, 

 competed with them. Hence, as a rule, wherever 



fossil corals are very abundant, Encrinites are not 

 so ; and contrariwise. This is markedly the case with 

 the Devonian limestones of England, where fossil co- 

 rals are very abundant, and Encrinites comparatively 

 rare, except in localities. In the Eifel Mountains, 

 the Crinoid family is better represented. One of 

 the few characteristic genera is Czipressocrim/s, or 

 "Cypress" Encrinite ; Haplocrimis is another. Platy- 

 crimis, a genus very abundant in the Carboniferous 

 limestone, makes its first appearance in the Devonian 

 strata. Its stem is naturally flattened or lenticular, 

 instead of being round, as is usually the case with 

 Palaeozoic Crinoids. The former part of its generic 

 name signifies "breadth," and is given to it on 

 account of the basal and radial plates of the body 

 being unusually broad in comparison with those of 

 other Encrinites. 



The Carboniferous limestone is undoubtedly the 

 metropolis of the Crinoids. During its deposition in 

 Europe, the number of genera and species reached 

 its maximum. They were never so numerous before ; 

 they have gradually been dwindling away ever since, 

 until our own epoch would seem to be that when their 

 final extinction would occur. Besides Rhodocrimis, 

 Platycrinus, and Poteriocrinus (already referred to), 

 we have the remains of such genera as Actinocrinus, 

 Cyathocrimis, Gilbertocrimis, Taxocrimis, Woodocrimis, 

 &c. Sometimes, as in the neighbourhood of Clithe- 

 roe, Lancashire, we get limestone seams composed of 

 heads of Encrinites, just as elsewhere we get beds 

 formed of their stems and arms. Cyathocrimis, 

 Actinocrinus, Platycrinus, and PoteriooiJiiis are the 

 commonest of Carboniferous genera, the latter being 

 profusely abundant in Ireland and Scotland, as well as 

 in every part of England where the Mountain or Car- 

 boniferous limestone appears. Actinocrinus is an 

 abundant fossil in places; its name of "radiated" 

 Encrinite being due to the thorn-like side-arms, 

 which project, at irregular distances, from the main 

 column. IFoodocrimis was named after Mr. Edward 

 Wood, of Richmond, in Yorkshire, its original dis- 

 coverer. Although not a very widely-distributed 

 fossil, it occurs in large quantities and in great per- 

 fection in the Carboniferous limestone at Richmond, 

 whence most of the finest specimens to be seen in 



j private and public collections have been obtained ; 

 thanks to the generosity of Mr. Wood, who worked a 

 small quarry for the sole purpose of obtaining 

 specimens. 



The Secondary Encrinites are mainly distinguished 

 from those of the Primary rocks by the fact that the 



' grooves in the arms are not arched over, but are con- 

 tinued over the central or upper surfaces. In Eng- 

 land, the only member of the New Red Sandstone 

 which yields fossil Encrinites — the Muschelkalk — is 

 absent. In Germany, especially in the hilly country 

 about Jena, where the Muschelkalk limestone crops 

 out, the Avell-known "Lily Encrinite" {Encrimis 

 inoniliformis), (fig. Ii8), abounds. In our Liassic 



