CONCHOLOGY. 



from forming hasty and erroneous conclu- 

 sions. 



Many of the cyprez, or cowries, when 

 young, have the appearance of a volute, 

 the thick denticulated fold of the exterior 

 lip being wholly wanting, and the column 

 being only partially plaited as in the true 

 voluta. The young of the alated shells, 

 in general, are destitute of that broad ex- 

 pansive or furcated lip, called the wing. 

 The spires ifi Tnany""ot the turretted kinds 

 of shells, when young, are blunt ; obtuse, 

 or terminated in a large globular head, 

 exceeding the size of the whorl beneath, 

 but as the shell 'advances in growth, it 

 developes itself, extending in a spiral 

 direction, and thus in the old shells the 

 number of spires is greater than in the 

 young- ones. The variations in the growth 

 of the patella tribe are often so conside- 

 rable, as to almost defy the critical ob- 

 server to determine them. Still, how- 

 ever, the conchologist, by the dint of ap- 

 plication and nice discrimination, will be 

 at last enabled to fix on certain charac- 

 ters peculiar to every species, and be, 

 by that means, enabled to decide on the 

 species of a shell under every stage of 

 growth. 



The primary character must be taken 

 from the shell, because this we are ac- 

 quainted with, while the animal is often- 

 times unknown to us. But the struc- 

 ture of the animal should be regarded 

 in the construction of genera, when it 

 can be ascertained, as a secondary consi- 

 deration to guide us in the formation of 

 new genera, or in correcting the old, 

 as opportunities of investigating them 

 occur. 



Having defined the meaning of a testa- 

 ceous animal, and endeavoured to prove 

 that the structure of the shell is the most 

 material object to be regarded in a pri- 

 mary view, we shall proceed next to an 

 elementary elucidation of the several 

 parts of which it is composed. 



In conchology, as in any other science, 

 the student must necessarily acquire, in 

 the first instance, a distinct knowledge of 

 the terms employ ed. Tin -,( , except such 

 as relate to subordinate characters, or 

 specifical distinctions, and which require, 

 no explanation in this place, may be sim- 

 plified and reduced to a small number. 

 In the selection of these terms we fan 

 abide by 110 one particular authority : 

 we must be general, deriving our terms 

 from various sources, or inventing new 

 ones. Hitherto, in treating on the diU'er- 

 ent articles of conchology, it lias beeiiour 



aim to adhere as nearly to the authority of 

 Linnaeus as possible. 



All shells or testaceous bodies, hitherto 

 discovered, may be divided into three 

 principal tribes, and which, after the Lin- 

 naean manner, may be denominated Mul- 

 tivalve, Bivalve, and Univalve. 



Any external part of a shell being of a 

 testaceous substance, and either itself 

 forming a shield or covering for the 

 animal, as in univalves, or in union with 

 another, or others connected by a liga- 

 ment, cartilage, hinge, teeth, or other 

 fastening, is denominated a valve. The 

 shells, therefore, consisting of a single 

 piece, are called univalves, those of two 

 parts bivalves, and those of many parts 

 multivalves. Between bivalve and multi- 

 valve no distinction is drawn, shells con- 

 sisting of more than two such parts 

 being called multivalve, without any 

 regaid to the number. An amendment 

 is proposed by some of the French wri- 

 ters, in a new order under the name of 

 trivalve. 



Shells ofthe simplest form are arranged 

 by some naturalists in the first class, 

 from which they proceed progressively 

 to those possessing the greatest number 

 of valves, and being of the most intri- 

 cate structure. This is an ancient and 

 very simple mode of arrangement, and 

 has its advocates in the present day. Lin- 

 nzeus reverses this order, by beginning 

 with the chiton, lepas, and pholas, which 

 are shells of the multivalve and most 

 complex structure, and ending with 

 those of the simplest form. The former 

 seems most preferable. 



Univalve. In the examination of a 

 shell of this order, the contour, or out- 

 line, is the first particular to be regard- 

 ed. By this the conchologist is guided 

 in his definition of simple, spiral, or tt:r- 

 binated shells, (or, as the Linnxan school 

 divides shells, univalves with a regular 

 spire, and univalves without a regular 

 spire ;) discoid, flattened, or turretted 

 shells ; those with smooth or uneven an- 

 fractus; the ventricose, alated, lahiateil, 

 rostrated, and many other distinction-., 

 all which strike the eye at the first view 

 It is, indeed, by attending tothe contour, 

 that the principal distinctions in slnl'. 

 of this kind are at once jx-iv/iv.-.l. taking 

 into consideration the hack and front pro- 

 file at the same time. Some lew slirlls, 

 as the nautilus pompilius, ami others of 

 the same family, hi\e the spire revolving 

 internally, in whieh the outline offer- 

 tance in the primary d linition* ; but 



