Chap. V. 
CONCHOLOGY. 
465 
Of the Con- ^ ec j es 0 f Shells which have been found in the Foffil 
State. 
Only found foffil. 
ftituent 
Parts of 
Shells, See. j j£pAS Anferifera. 
65 Cardtum Lithocardium. 
Found foffil. Venus Caffma. 
- Mercenaria. Mountains of Sweden. 
„ Imbricata. France. 
ChaMA Foliacea. Campania. 
Arca Foffilis. Limbourg. 
■ Nucleus. 
Ostrea Diluviana. Sweden. 
Mytiloides. Alface. 
_ — . Torta. Alface. 
Anomia Craniolaris. 
— — Gryphu-s. 
- — ■ Peften. 
— - Striatula. Ex-ids only foffil. 
— — — — Reticularis. 
Plicatella. Only foffil. 
— - Crifpa. England and Switzerland. 
Lacunofa. Only foffil. 
Cufpidata. Derbylhlre. 
— Farfta. Switzerland. 
= — , Terebratula.. 
— Angulata. 
— Hyfterita. Germany. 
- Biloba. Only foffil. 
• Spinofa. England. 
Dorfata. 
_ Sandalium. Germany. 
Nautilus Helicites, 
■ — Lituus. 
— — Orthocera. 
— — ■ — — Belemnita. 
Voluta Foffilis. Only foffil. 
Buccinum Foffile. Germany. 
— -- Marginatum. 
Strombus Spinofus. Only foffil. 
— Fiffurella. Campania. 
- — Sinifter. Foffil only. Helvetia. 
Murex Triacanthus. 
— Triptenus. Campania. 
. Coftatus. Campania. 
Lsevigatus. Campania. 
— Foffilis. Campania. 
Campanicus. Campania. 
Trochus Sell rosteri. Campania. 
Nerita Clathrata. Campania. 
Perverfa. Only foffil. 
Haliotis Perverfa. 
Plicata. 
Patella Echinata. 
Dentalium Sexangulum. Loretto, 
» Foffile. Loretto. 
Annulatum. 
— Radula. Piedmont. 
Interruptum. 
— Vitreum. Piedmont. 
Serpula Seminulum. 
, — Melitenlis. Malta. 
Of the Con- 
diment 
Parts of 
Shells, 8tc. 
CHAP. V. OF THE CONSTITUENT PARTS OF SHELLS, &c. 
HAVING in the former chapter enumerated, under 
each genus, all the fpeeies of teftaceous animals which 
have been hitherto difeovered ; and having given the 
characleriftic marks by which each is diftinguiffied, 
which marks are derived from the (hell or teftaceous 
covering ■, we now propofe to inquire what is the na- 
ture of this fubftance 3 in what way it is produced by 
the animal, and how it is enlarged as the animal in- 
creafes in fize. Thefe topics fhall be the fubjefl of 
the prefent chapter, which may be conveniently divid- 
ed into the following factions. 1. Of the conftituent 
parts of Ihells. 2. Of their formation. 3. Of the 
colours of Ihells. 4. Of the formation of the umbilicus 
and protuberances, &c. 5. Of the pearl. 
Sect. I. Of the Conftituent Parts of Shells. 
The nature and component parts of teftaceous fab- 
ftances have been particularly inveftigated by Mr Hat- 
Pbil.Tranf chett, from whofe paper we extract the following ob- 
1799 • fervations. 
. p In his examination of marine Ihells, Mr Hatchett 
flieUs from found, from the nature cf the fubftance of which they 
their com- are compelled, that they might be arranged in tiro di- 
ponent villons. Under the firft are included thofe which have 
? auSl a porcellaneous appearance and enamelled furfaee, and 
exhibit, when broken, fomething of a fibrous texture. 
The other divilion is diftinguiffied, by having a ftrong 
epidermis or covering, under which is the ffiell, com- 
pofed , principally or entirely of mother-of-pearl. To 
Vol. VI. Part II. 
the firft divilion belong different fpeeies of voluta, c y- 
prsea, and others. The fecond comprehends the oyf- 
ter, the river muffel, and fume fpeeies of haliotis and 
turbo. <58 
Porcellaneous foells .— The (hells of this defeription Porcelisae 
which were examined, were different fpeeies of volu- odr - 
ta and cyprsea. When they were expofed to a red 
heat for a quarter of an hour, they crackled, and loll 
the colours of their enamelled furfaee. No apparent 
fmoke, and no fmell, like that of burnt horn or carti- 
lage, were emitted during the procefs. The figure 
remained the fame, excepting a few flaws 5 and they 
became of an opaque white, partially tinged with pale 
-gray. When they were diffolved in acids, after being 
burnt, they depofited a fmall quantity of animal coal, 
which proves that they contain feme portion of glu- 
ten. Shells which had not been expofed to the fire, 
diffolved with great effervefcence in the different acids ; 
and the folution remained tranfparent and colourlefs 5 
from which it appears, that the , proportion of gluten 
is fmall, fince it could not be traced id the folution of 
the unburnt (hells. 
In examining the different foiutlons of (hells, whe- 
ther burnt or unburnt, by chemical tells, it was found, 
that' no trace of phofphate of lime, or of any other 
combination of phofphoric acid, exifted In thefe fub- 
ftances. And it appeared from many experiments, that 
the component parts of porcellaneous (hells, are car- 
bonate of lime, cemented with a very fmall portion of 
animal gluten, 
3 N 
Some 
