BELEMNITES. 



373 



as ornamental plants. Tlicy yield an acid juice as 

 has been already stated, and their roots are bitter 

 and astringent. 



The only genus is Begonia, whence the name of 

 the order is derived. Many of the species are cul- 

 tivated on account of the neatness of the foliage, 

 and the showy nature of their flowers. The silver- 

 spotted and two-coloured Begonia are the most beau- 

 tiful species. 



.Bicolour Begonia. 



The genus is remarkable for the peculiar obliquity 

 of the two sides of its leaves, which, in the Begonia 

 bicolor, resembles the ramifications of the blood 

 vessels in the human frame. 



Begonia grandsflora and tomentosa are mentioned by 

 Decandolle as being used in Peru, on account of their 

 astringency, in fluxes of blood and diseases of the 

 chest. 



BELEMNITES. A fossil found in great abun- 

 dance in most of the formations from the Has upwards. 

 The origin of these singular productions has at all 

 times been involved in great obscurity, as nothing 

 analogous to them in form has been observed amon 

 living animals ; and it is curious to observe the 

 different opinions which mankind in various ages have 

 held respecting their production. 



They were known to the ancients. Ovid, in the 

 15th book of his Metamorphoses, assigns them a very 

 fanciful origin ; whence they received the name of 

 Lapides Lynces, Lynciirium, &c. They were also 

 known by the denomination of Idceus Dactylits, 

 possibly from their resemblance to fingers, and also 

 from their having been found on Mount Ida. 



Among the northern nations it was a common 

 opinion that these stones were petrified fingers, 

 fabricated by demons, in order to be used in those 

 mysterious rites of supernatural agency of which their 

 fierce and gloomy superstition fostered the belief. 



By them they were designated by terms referring to 

 such agency, their common names being those of 

 " Devils' Fingers" " Spectorum Candda, n &c. 



As fossils came to be better understood, the belem- 

 nite was supposed, on account of its conical cavity, 

 either to be the remains of the tooth of some unknown 

 animal, or, as it was usually found associated with 

 marine productions, a spine similar to that of the 

 echinus. 



When at length, with the advance of science, it 

 came to be considered as the remains of a testaceous 

 animal, new theories and conjectures arose. It was 

 first supposed to be a dentalium, then a limpet ; but 

 further observations at last proved it to be the 

 remains of a univalve shell, divided into chambers, 

 pierced by a tube, and similar in their construction to 

 those of the nautilus, which was inclosed in an outer 

 case or sheath, having a sparry mineral structure, ra- 

 diating from an axis, passing perpendicularly through 

 the fossil, which, in its most perl'ect state, is formed 

 of carbonate of lime. 



When perfect, it presents the appearance of two 

 conical shells, the apex of the one being inserted into 

 the base of the other. 



Its general appearance is that of a straight, elon- 

 gated, conical shell, formed of two distinct and sepa- 

 rate parts. The external being a solid sheath, having 

 a conical cavity in the upper part, which contains an 

 internal conical nucleus, which is pointed and cham- 

 bered transversely thspugh its whole length. The 

 chambers are slightly concave on the one side, and con- 

 vex on the other, perforated by a lateral siphuncle. 



The outer case is most commonly found without 

 the nucleus, being merely the sheath, of the internal 

 conical mass ; its form is that of a long cone, more or 

 less pointed ; and it often has a lateral groove ; it 

 becomes solid as we approach the apex, whilst the 

 buse is perforated by the conical cavity before men- 

 tioned, lor the reception of the multilocular nucleus. 



BeJemr.ites. 



This cavity is not always placed in the centre of the 

 cone, there being numerous instances of its being 



