NOTES AND QUERIES. 



299 



the outer and inner plates entire, and supported only by thin partitions. Speci- 

 mens exhibiting these appearances are full of small oblong cells, connected by 

 linear perforations, wliich are either empty or filled with chalk or flint ; in the 

 latter case they give rise to a curious class of fossils, the nature of which the late 

 Rev. Mr. Conybeare has given an ingenious explanation in the second volume of 

 the ' Geological Transactions.' These fossils being the siliceous casts of such 

 excavated cells. 



" /S/)o??(/es, many varieties (branched, conical, and round).— Elongated pieces of 

 smooth round flint often occur, having a cavity filled with another flint, cor- 

 responding to the cavity, which on breaking is found to be white and enamelled on 

 the outside. Many such occm*, having thus a flint within a flint-sheath. Splendid 

 specimens of mammilated chalcedony are sometimes found in the hollows left by 

 decomposed sponges in flints. The writer once saw a specimen about nine inches 

 by six, Avith the mammillae of the size of large grapes, and of a beautiful blue 

 colour. This mammillation is the cause of the chalcedony, occasionally, in the 

 landscape-agates assuming, when cut and polished, a hammered appearance, like 

 the marks left by the Avorkmen on copper, and is from that cause vulgarly called 

 ' hammered chalcedony.' 



" Foraminifera. — By means of a small lens I have been enabled to detect several 

 species. Lituola Nautiloidea, and Placopsilina irregularis, are the most prominent, 

 and can often be detected with the naked eye. 



Micraster cor-anguinum, Ananchytes ovatus, Galerites alhogalerus, Cidarites 

 (several varieties), Marsupites (plates of), Eschara disticha, Ehyndionella octopUcata, 

 JR. subplicata, Terehratvla senuglobosa, T. suhrotunda, T. carnca, Magas p>uniilusj 

 Ostrea vescicidaris (and other species), Fecten quinque-costatus, Inocermnus 

 LcmarcJcii (and other species), Plagiostoma Hoperii, Spondylus spinosum. — These 

 last are generally found on the outside of the flints, in a remarkable state of 

 preservation ; they are also found, although less often, in the body of the flint. 



" Area (species of), Beleranites. — Casts of two or three varieties of the latter are 

 found, but in most cases nothing is left of the body of the fossils but a hollow 

 tube-like cavity, with the cast of the phragmacone." 



Encrinites and Crinoids.— " Dear Sir, — Will you kindly inform me if the 

 Encrinite be a species of Crinoid \ My reason for askhig is, that M'Causland, 

 in his ' Sermons in Stones,' fourth edition, p. 51, states that the Encrinite ' is 

 a species of Starfish fixed on the top of a flexible stalk, vising from and fastened 

 to the bottom of the water ;' and in the first number of The Geologist I find 

 under the head of ' Woodocrinus,' a description of its stem as being ' invariably 

 tapering,' so that the longer it is the thinner it becomes. This circumstance 

 would lead us to imagine, that the creature floated freely in the Avater, and that 

 the stems were used to balance it, and keep it upright while it floated. Should 

 this fact be established, it will place this genus between the free Comatula and 

 the fixed Crinoid. The Comatula here mentioned as ' free,' is noticed in M'Caus- 

 land's work as ' the existing representative,' Avith the Pentacrinus Caput- Medusa;, 

 of the primeval Encrinite. — I am, Sir, yours truly, M. C. H."— Crinoids, or 

 Crinoidea, is a general family name for the many genera of Encrinites, Actino- 

 crinites, Pentacrinites, Apiocrinites, &c. The generic name of Encrinites is some- 

 times loosely used for the same purpose, having been the word adopted by old 

 natm'alists for these creatures. But the generic name Encrinus having been 

 restricted in modern nomenclature to the BrunsAvick Encrinite, the word Crinoidea 

 is better adapted as a general family term. Still Crinoid and Encrinite are used 

 by authors indifferently. Both our correspondent and M'Causland (as quoted) 

 use the Avord " species " in a loose sense for " kind." Most Crinoids were fixed 

 by roots at the end of their stems, but the Woodocrinus appears to have been one 

 of the exceptions, and seems to have been destitute of them. It might possibly 

 have floated, but more likely it grovelled in the mud or sand, or lolled on the coral 

 banks. 



Frogs in solid Stone and in Trees ; living Spiders in Flint. — " Dear 

 Sir, — Sometimes, in regarding one special class of facts, we are apt to overlook 

 others of a similar nature, from which much knowledge may be gained. In 

 referring to vol. xxxix. of the ' Gentleman's Magazine' (1769) for another purpose 



