720 GEOLOGY. 



found in the lias at Whitby and Lyme Regis have been met with at a great eleva- 

 tion in the maritime Alps, and also at the height of 16,000 feet in the Himalaya 

 mountains. These molluscous animals appear to have preyed upon humbler molluscs, 

 crustaceans, and perhaps fishes, thus keeping the races within bounds. They were 

 adapted, by the organisation of their shells, equally to float at the surface of the sea and 

 to visit its profound depths at pleasure. A thin and light shell, with successive air 

 chambers, qualified them for the former purpose, while a general arch-like form, strength- 

 ened by a series of ribs or transverse arches, enabled the shell to resist the great pressure 

 of the superincumbent water when at the bottom of the sea. This is another of the ten 

 thousand instances exhibited by the various departments of nature, of ingenious contriv- 

 ance to meet peculiar circumstances, which as clearly demonstrates the existence of a 

 wisely-designing First Cause, as the arch of a bridge, or the groined roof of a Gothic 

 cathedral, attests the action of an intelligent artificer. Nothing better displays the advan- 

 tage of knowledge than the information we now have respecting the economy of the 

 Ammonites, and the inferences deducible therefrom, contrasted with the views current in 

 former ages of these organic remains. They were the lusus naturce of the learned, the 

 petrified ram's horns of the vulgar, and the snakes decapitated and turned into stone, by 

 the prayers of St. Hilda, of the superstitious. A similar legend to that of the north of 

 England belongs to a locality in the south, which recognises St. Keyna surrounded by 

 serpents in a wood at Keynsham, between Bath and Bristol, changing them into head- 

 less stones by the fervour of her devotions. 



Belemnites, another extensive extinct family of molluscs, belonging to the same 

 division as the Ammonites, termed cephalopodous, from their organs of motion being 

 arranged around the head, make their first appearance in England in the lias, and 

 prevail through the oolite and chalk, but on the Continent they occur in strata of the 

 subjacent system. These fossil bodies are the thunderstones of the populace, for before 

 their organic animal origin was suspected, they were supposed to be concretions produced 

 by electricity. By the ancients they were c&lled^ldcei dactyli or petrified fingers, from 

 being found on Mount Ida, and from their supposed resemblance to those organs ; while 

 to the northern nations, whose imagination was of a gloomy cast, they were known 

 as the devil's fingers, and as spectre candles. The Belemnites, of which there are 

 millions of individuals, belonging to between eighty and ninety species, derive their 

 scientific name from their similarity to the head of a dart or javelin. They generally 

 occur as cylindrical stones, pointed at one extremity, with a cavity at the other end, 

 which is either filled up with a chambered? shell, or with the material of the stratum in 



which the fossil has been imbedded. They 

 vary from a very small size to several inches 

 _ in circumference, and nearly a foot in length. 



Belemnites pistiliformis. J 



An example of one species, is here given ; 



but we have only here a subordinate part of the original structure of the animal, 

 called the ossekt, performing the office of a guard or sheath. Recent discovery has proved 

 that the ancient Belemnite corresponded to the Sepia, or cuttle-fish, in being furnished 

 with an ink-bag, ejecting the fluid at pleasure, as a means of defence against enemies, or by 

 way of covering its retreat from them. It is a remarkably curious fact, that a substance 

 so easily destroyed as the ink-bag and its contents should have been found perfectly 

 preserved in the lias limestone of Lyme Regis. Dr. Buckland infers from this circum- 

 stance that the animals must have died suddenly, for their living analogues eject the inky 

 fluid upon the least approach of danger. It is very rare to find a specimen complete in 

 all its parts, probably owing to the imbedding stratum which is favourable to the preser- 

 vation of one portion being unfavourable to that of another. But a few perfect examples 



