1854.] 



CHEMICAL COMPOSITION OF FOSSIL LINGUL^E. 



265 



phosphate of magnesia, equal to '044 of phosphoric acid, or -0978 

 of phosphate of lime, P0 5 , 3CaO. 



The lime was separated from the acetic filtrate, as an oxalate, 

 and gave -108 of carbonate, equal to -0505 of lime, being an ex- 

 cess of •0075 over the amount required to form the phosphate, 

 and corresponding to -01 34 of carbonate; the small amount of 

 materia] did not permit us to determine whether a portion of the 

 lime exists as fluoiid. There was also obtained -0032 of mag- 

 nesia; the results from the calcined shell of Lingula ovalis are 

 then as follows: 



Phosphate of lime, -0978 = 85-79 per cent. 

 Carbonate of lime, -0134 = 11-75 

 Magnesia, - - -0032 = 2 80 



•1144 = 100-34 



The proportion of phosphate of lime is that contained in 

 human bones, after their organic matter has been removed. 



The texture of the ancient Linguke was observed to be unlike 

 that of most other fossil shells, being more or less dark brown in 

 color, brilliant, almost opaque, and not at all crystalline. These 

 characters are also found in the allied genus Qrbicula, and we 

 therefore examined an undescribed species of it, from the Trenton 

 limestone, beautifully marked in a manner resembling Conularia 

 granulata, and another large species, also undescribed, from the 

 Upper Silurian; both of these consist chiefly of phosphate of 

 lime ; and the shell of a recent species, 0. Lamellosa from Callao, 

 was found to be similar in composition. We have not yet been 

 able to examine a specimen of the genus Obolus. The same 

 dark color and brilliancy were also remarked in the genus Conu- 

 laria, and the shell of C. trentonensis proved on examination to 

 be composed in like manner of phosphate. 



The similarity of composition in these genera is in accordance 

 with the acute observations of Mr. Hall, who finds that Conularia 

 is almost always associated with Lingula and Orbicula, and re- 

 marks that " these shells, so unlike in structure and habit, appear 

 to have flourished under similar circumstances, and to have re- 

 quired the same kind of oSean bed or sediment." — Palaeontology, 

 vol. 1, p. 101. 



For the sake of comparison, we have examined the following 

 fossil shells : they have a common character, distinct from those 

 already described, being lighter coloured, more translucent and 

 granular in texture; Atrypa extans, Leptama alter nata, andOr- 

 this peetenella from the Trenton limestone; O. erratica from the 

 Hudson River group, and Chonetes lata (?) from the Upper 

 Silurian, besides Isolelus gigas, and a species of Cythere from 

 the Trenton. All of these consist of carbonate of lime, with only 

 such traces of phosphate as are generally found in calcareous 

 shells. 



In the report already quoted we have given a description of 

 some phosphatic bodies which resemble the coprolites of the 

 calciferous sandstone, and are found at Riviere Ouelle in thin 

 layers of a conglomerate limestone, which is interstratified with 

 red and green shales, and belongs to the top of the Hudson River 

 group or the base of the Oneida Conglomerates. The phosphatic 

 masses are very abundant, and rounded, flattened, or cylindrical 

 in shape, and from one-eighth of an inch to an inch in diameter; 

 they sometimes make up the larger part of the conglomerate. 

 Iron pyrites in small globular masses occurs abundantly with 

 them, often filling their interstices, but is not found elsewhere in 

 the rock. These coprolites are finer grained and more compact 

 than those from the Ottawa, and have a conchoidal fracture ; 



their color is bluish or brownish black; the powder is ash-grey, 

 becoming reddish after ignition. They have the hardness of 

 calcite and a density of 3-15. When heated they evolve ammo- 

 nia with an animal odor, and with sulphuric acid give the reactions 

 of fluorine. The quantitative analysis of one gave — 



Phosphate of lime, P0 5 , 3 Ca O, - 4034 p. c. 

 Carbonate of lime, with fluorid, - 5-14 

 . . Carbonate of magnesia, - - 9'70 



Peroxyd of iron, with a little alumina, 12-62 

 Oxyd of manganese, - trace. 



Insoluble silicious residue, - - 25-44 

 Volatile matter, ... 2-13 



95-37 



The iron exists in part at least as carbonate, and its introduction 

 in so large a quantity, giving color and density to the coprolites, 

 is doubtless connected with the formation of iron pyrites by the 

 de-o.\ydizing action of organic matters. The production of an 

 equivalent of bisulphuret of iron, from a neutral protosulphate of 

 iron, which alone could exist in contact with limestone, must be 

 attended with the elimination of an equivalent of protoxydof iron; 

 for 2(SOs.Fe O)— 7=Fe S2+Fe O. 



It is remarkable that no traces of Lingulae or any other shells 

 have been detected with these coprolites. Thin sections of them 

 are translucent, and under the microscope are seen to consist of a 

 fine granular base, in which are imbedded numerous grains of 

 quartz, and small silicious spicula?, like those of some sponges. 

 In a bed of sandstone, associated with these conglomerates and 

 slates at Riviere Ouelle, were found several hollow cylindrical 

 bodies, resembling bones in appearance. The longest one is an 

 inch and a half long, and one-fourth of an inch in diameter. It 

 is hollow throughout, and had been entirely filled with the cal- 

 careous sandstone, in which it is imbedded, and whose disinte- 

 gration has left the larger end exposed. The smaller extremity 

 is cylindrical and thin, but it gradually enlarges from a thickening 

 of the walls, and at the other, end becomes externally somewhat 

 triangulariform ; the cavity remains nearly cylindrical, but the 

 exposed surfaces are rough and irregular within. 



The texture of these tubes is compact, their color brownish 

 black with a yellowish brown translucency in thin layers. Ana- 

 lysis shows them to. consist, like the coprolites, principally of 

 phosphate of lime. One hundred parts gave — 



Phosphate of lime, - - - - 67-53 

 Carbonate of lime, - - - - 4-35 



Magnesia, - - - - - 1-65 



Protoxyd of iron, - 2-95 



Insoluble silicious sand, - - - 21-10 



Volatile, animal matter, - - - 2-15 



99-73 



The microscopic examination of a section shows that the walls 

 of the tube are homogeneous, unlike the coprolites, and that the 

 silicious sand in the analysis came from the sandstone which in- 

 crusted the rough interior of the fossil. The phosphate is finely 

 granular, and retains no vestige of organic structure. The che- 

 mical composition and the remarkable shape of the specimens, 

 however, leave little doubt of their osseous nature, unless we 

 suppose them to be the remains of some hitherto unknown inver- 

 tebrate animal, whose skeleton, like those of Lingula, Orbicula, 

 and Conularia, consisted of phosphate of lime, a composition 

 hitherto supposed to be peculiar to vertebrate skeletons. 



Montreal, January 5th, 1854. 



