BULLETIN OF THE BUSSEY INSTITUTION. 193 
In the axes of various sea-pens (Pennatula), Fremy * found from 31.2 
to 48% of ashes. A more complete analysis of the axes of two kinds of 
Pennatula gave the following results: — 
I. Ii. 
Organic matter, insoluble in acids . . 16.40 11.10 
7” soluble 3 « & 31664 19.33 
Carbonate MOL) 2. wil. sh vel pe dds 53.57 
Phosphate _,, Betas anid dak Mears: aii oak 16.00 
Mipouoespnoric acid . . . .. . . 10.86 7.33] 
An important exception to the general rule, that sea-shells consist 
chiefly of carbonate of lime, was detected by Logan and Hunt,t by whom, 
and by Cloez ft also, several years later, it has been shown that some kinds 
of shells, such as were specially abundant in the waters of the earliest 
geologic periods, contain a very large amount of phosphate of lime. Lo- 
gan and Hunt found not only that fossil-shells of the Lingule, which oc- 
cur in the lower Silurian rocks, consist chiefly of phosphate of lime, but 
that the shells of existing species of Lingula are equally phosphatic. They 
examined particularly Lingula prima and L. antiqua from the Potsdam 
sandstone, ZL. parallela from the calciferous, and a species somewhat re- 
sembling L. guadrata from the Trenton limestone; all of which shells, it 
is to be noted, dissolved readily in dilute chlorhydric acid, with slight 
effervescence. The shell of a recent species (Lingula ovalis) from the Sand- 
wich Islands was found to have the same composition as the fossil-shells; 
the thick, green epidermis, which swelled up like horn when heated, gave 
a bulky, white ash of phosphate of lime. On being calcined over a spirit- 
lamp, the shell, with its epidermis, lost 38.6% of its weight; and the cal- 
cined shell contained 85.79% of phosphate of lime (equivalent to 39.30%, 
of phosphoric acid), 11.75% of carbonate of lime, and 2.8% of magnesia. 
‘¢'The proportion of phosphate of lime is that contained in human bones 
after their organic matter has been removed.’ 
Cloez found in shells of Lingula anatina, dried at 100°, 45.20 of or- 
ganic matter, 42.290/, phosphate of lime, 8.850, phosphate of magnesia, 
6.689% carbonate of lime, and 1.984% phosphate of iron, and traces of 
silica. The organic matter contained nitrogen and sulphur. 
Logan and Hunt found, furthermore, that an undescribed fossil species 
of Orbicula from the Trenton limestone, and another large undescribed 
species of Orbicula from the upper Silurian as well as the shell of a recent 
species (O. lamellosa) from Callao, consisted like the Lingula shell, chiefly 
of phosphate of lime. The shell of Conularia trentonsis also proved, on 
examination, to be largely composed of phosphate of lime. 
For the sake of comparison, Logan and Hunt examined a number of 
other fossil shells, viz., Atrypa extans, Leptena alternata, and Orthis pec- 
* “ Annales de Chimie et de Physique,” 1855, 43. 98. 
+ “ American Journal of Science,” 1854, 17, 235. 
t Kopp and Will’s “ Jahresbericht der Chemie,” 1859, 12. 642. 
VOL. Il. 13 
