. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. make additional observations on some specimens from Gera, with one of Smith and Beckys highest-class binocular microscopes, for the use of which I am indebted to its owner, Dr. Rowney. I shall now relate the results of my last investigations. In order to ensure an examination of the entire thickness of the valves, I operated on specimens partially imbedded in their matrix, which is siliceo-calcareous and granular. Figure 1 represents a polished medio-longitudinal section of on
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. make additional observations on some specimens from Gera, with one of Smith and Beckys highest-class binocular microscopes, for the use of which I am indebted to its owner, Dr. Rowney. I shall now relate the results of my last investigations. In order to ensure an examination of the entire thickness of the valves, I operated on specimens partially imbedded in their matrix, which is siliceo-calcareous and granular. Figure 1 represents a polished medio-longitudinal section of one of these specimens, about thrice its natural size. The in- terior is filled with calcite. The letter a refers to the matrix, which adheres to a considerable portion of the perforate valve. In this case, there can be no doubt that the extra- neous mineral matter covers the ori- ginal outer surface of the fossil. At the umbonal region, b, the external layers of the test are not present, having got detached along with the matrix before the specimen came into my hands: the surface exposed at this part, as well as that of the imperforate valve, displays numerous dark-coloured spots, resembling those resulting from tubulation in many Palliobranchs, particularly the Carboniferous Spiriferina octoplicata, in which, however, they are larger. Figure 2 represents a portion, from below the letter «, of the last section, as seen under a mag- nifying power of 120. Two of the tubes are insufficient for our pur- pose, having been broken short of their length by the removal of the outer layers and matrix; but the next one is conclusive, as it passes completely through the valve. The fourth or adjoining tube does not appear to reach the ex- terior. Figure 3 represents a portion of a similar longitudinal sec- tion, as seen under the same power. It shows two tubes tra- versing the thickness of the valve to the outer surface, and a third one apparently passing to within a very short distance of
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Keywords: ., bookce, booksubjectbotany, booksubjectgeology, booksubjectzoology
