Microscopic Journal, and Structural Record . magnified 310 diameters, and representing portions ofvarious degrees of thickness. These may be con-sidered in some de-gree as a type of thehairs of rodents ge-nerally. The formof the hairs is notshewn in these fi-gures, but they arecircular, or slightlycompressed, and ta-pering towards eachextremity, and usual-ly thicker towardsthe point. Internally6 7 8 9 tubular, and furnish- ed with cells of nearly uniform size, containing black colouring the thicker hairs these cells are arranged alternately in two, three,or more rows, and they are lo
Microscopic Journal, and Structural Record . magnified 310 diameters, and representing portions ofvarious degrees of thickness. These may be con-sidered in some de-gree as a type of thehairs of rodents ge-nerally. The formof the hairs is notshewn in these fi-gures, but they arecircular, or slightlycompressed, and ta-pering towards eachextremity, and usual-ly thicker towardsthe point. Internally6 7 8 9 tubular, and furnish- ed with cells of nearly uniform size, containing black colouring the thicker hairs these cells are arranged alternately in two, three,or more rows, and they are lost towards both extremities. The externalsurface is composed of regular, imbricated, adpressed, somewhat roundedscales. Hairs of the Sable, magnified 620 diameters. These may be con-sidered typical of thefiner hair or down ofthe weasel tribe, whichat first sight much re-sembles that of ro-dents ; from which,however, the larger hairs will be found to differ more materially. These hairs are compressed, tapering to each extremity, but thicker. WHITE ON FOSSIL XANTHIDIA. 35 towards the base. Internally, hollow, and furnished with colour cells,which will afterwards be referred to. Externally, covered with elon-gated, imbricated scales, not very closely adpressed. Towards thepoint for some distance the colour cells disappear, and the scales assumea very different form. The point usually appears broken off, as in Fig. 11. VI.— ON FOSSIL XANTHIDIA.* By Henry Hoply White, Esq. This interesting portion of fossil Infusoria called Xanthidia,in the recent state forming a genus of the tenth family of the classPolygastrica, called Bacillaria, has, in this genus, the animalculeunattached and free from any pedicel, of a globular form, gene-rally spherical, but in ome of the species occasionally of an irre-gular oval. With one exception, all the species of this genus havethe lorica or external covering semi-transparent, and invested with ten-tacula, which vary in form, number, and dimensions.
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Keywords: ., bookcentury1800, bookdecade1840, bookpublisherlondon, bookyear184
