336 Messrs. W. E. Logan and T. S. Hunt on the 



of animal matter : the same thing was observed with those from 

 Greuville. 



The existence in Lower Silurian rocks, of these masses, whose 

 characters leave no doubt that they are coprolites, and whose 

 chemical composition is like that of the excrements of creatures 

 feeding upon vertebrate animals, led us to examine the shells of 

 the LingulcB always associated with these phosphatic bodies. The 

 result has been that all the specimens yet examined consist 

 chiefly of phosphate of lime; they dissolve readily with slight 

 eflfervescence in hydrochloric acid, and the solution gives with 

 ammonia a copious precipitate readily soluble in acetic acid, from 

 which oxalic acid throws down lime. With a solution of molyb- 

 date of ammonia there is obtained a quantity of the characteristic 

 yellow molybdo- phosphate, many times greater than the bulk of 

 the shell. 



We have thus examined Lingula prima and L. antigua from 

 the Potsdam sandstone, L. parallela from the calciferous, and a 

 species somewhat resembling L. quadrata from the Trenton 

 limestone. It was desirable to compare with these the shell of 

 a recent species, and for this purpose tine specimens of the Lin- 

 gula ovalis, of Reeve, from the Sandwich Islands, were furnished 

 us by J. H. Redfield, Esq., of New York. The shell of this 

 species had the same composition as the fossil ones ; and the 

 thick, green epidermis, which swelled up like horn when heated, 

 gave a bulky white ash of phosphate of lime. 



For a further analysis, the shell was boiled in water to remove 

 all soluble matters, the soft parts still adherent were carefully 

 detached, and the shell with its epidermis weighing "186 grm., 

 was calcined over a spirit-lamp. The brownish residue, weigh- 

 ing •114 grm., readily dissolved with slight effervescence in 

 dilute hydrochloric acid, leaving but a few light flakes of car- 

 bonaceous matter. Acetate of soda and perchloride of iron were 

 added to the solution, which was boiled, and the precipitated 

 basic salt separated by filtration and decomposed by hydrosul- 

 phuret of ammonia. The filtrate from the sulphurct of iron 

 ha\ing been concentrated, the phosphoric acid was thrown down 

 by ammonia with a magnesiau salt; there was obtained "070 

 grm. of pyrophosphate of magnesia, equal to '044 of phosphoric 

 acid, or -0978 of phosphate of lime, P0^ 3CaO. 



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

 and gave '108 of carbonate, equal to •0605 of lime, being an 

 excess of ^0075 over the amount required to form the phosphate, 

 and corresponding to -0134 of carbonate; the small amount of 

 material did not permit us to determine whether a portion of the 

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

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



