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, which 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 exiilanation in the second volume of 
the 'Geological Transactions.' These fossils beuig the siliceous casts of such 
excavated cells. 
" -S/wH5fc«, many varieties (branched, conical, and round).— Elongated pieces of 
smooth round flint often occm-, 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 occiu-, having thus a flint within a flint-sheath. Splendid 
snecimens of mammilated chalcedony are sometimes found in the hollows left by 
decomposed sponges in flmts. The writer once saw a specimen about nine inches 
by six, with the mammillaj of the size of large grapes, and of a beautiful blue 
coloiu:. 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 woi-kmen on copper, and is fi-om 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-anguinmn, Ananchytes ovatus, Galerites albogalerus, Cidarites 
(several varieties), Marsupites (plates ot), Eschara disticha, HhynchoneUa octoplicata, 
R. subplicata, Terebratula semiglohosa, T. suhrotunda, T. carnea, Mayas pxunilus, 
Ostrea vescicularis (and other species), Pecten qidnque-cosiatus, Jnoceramus 
Lamarckii (and other species), Plagiostoma Hoperii, Spcmdylus spinosum. — These 
last are generally found on the outside of the flints, m a remarkable state of 
preservation ; they ai'e also found, although less often, in the body of the flint. 
" Area (species of), Belemnites. — 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 phi-agmacone." 
Encrinites and Crixoids. — " Dear Sir, — WiU you kindly inform me if the 
Encrinite be a species of Crinoid ? My reason for asking is, that M'Causland, 
in his ' Sermons in Stones,' fomth edition, p. 51, states that the Encrinite ' is 
a species of Starfish fixed on the top of a flexible stalk, rising from and fastened 
to the bottom of the water ;' and in the fii'st number of The Geologist I find 
under the head of ' Woodocrtnus,' a description of its stem as being ' invariably 
tapering,' so that the longer it is the thinner it becomes. This circimistance 
would lead us to imagme, that the creature floated freely in the water, and that 
the stems were used to balance it, and keep it upright while it floated. Should 
tliis fact be estabhshed, it will place this genus between the free Comatula and 
the fixed Crinoid. Tiie Comatula here mentioned as ' free,' is noticed in M'Caus- 
land' s work as ' the existing representative,' with the Pentacrimis Caput- Medusce, 
of the primeval Encrinite. — I am, Su', yours tnily, M. C. H."— Crinoids, or 
Crinoidea, is a general famUy name for the many genera of Encrinites, Actino- 
crinites, rentacrinites, Apiocrinites, &c. The generic name of Encrinites is some- 
times loosely used for the same pm-pose, having been the word adopted by old 
naturaUsts for these creatures. But the generic name Encrinus having been 
restricted in modem nomenclatiue to the Bnmswick Encrinite, the word Crinoidea 
is better adapted as a general family temi. Still Crinoid and Encrinite are used 
by authors indifferently. Both om- correspondent and M'Causland (as quoted) 
use the word " species" in a loose sense for " kind." Most Crinoids were fixed 
by roots at the end of then 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 hkely 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 natm-e, from which much knowledge may be gained. In 
referring to vol. xxxix. of the ' Gentleman's Magazine' (1769) for another purpose 
