IDopttTar JBtcttonarj) at gtoimatctt $ature. 



13 



habit of burrowing in the sand, in which 

 they find the worms and insects that con- 

 stitute their chief food. They are in their 

 turn preyed upon by the larger fishes, par- 



ticularly by the mockarel and salmon ; to 

 the support of the latter, whilst they are in 

 the estuaries of rivers, the Launcea are be- 

 lieved to contribute largely. The Launce 

 spawns in the month of May, depositing its 

 eggs in the mud, near the edges of the 

 coast. 



AMMODYTES. A genus of Serpents, 

 nearly the size of the Viper, and allied to it 

 in general appearance, though distinguished 

 from it by an erect pointed process on the 

 tip of the snout : its usual colour is either 

 bluish-grey or brown, with a continued black 

 dorsal band resembling that of the viper. 

 A species of this genus is found in many 

 parts of the East, and is so extremely poi- 

 sonous as to prove fatal in three or four noun. 



AMMONITES, or SNAKE-STONES. 

 Spiral fossil shells, of which there are a great 

 abundance in Europe, Asia, and America, 

 especially in the lias, chalk, and oolite for- 

 mations. They appear like a snake rolled 

 up : some are very small, but occasionally 

 they are met with upwards of three feet in 

 diameter. In some places they are so nu- 

 merous, that the rocks seem, as it were, 

 composed of them alone. Upwards of 240 



species have been already described ; and it 

 appears that many of these were very widely 



distributed ; some being found in the Hima- 

 laya mountains, at an elevation of 16,000 

 feet, and others in various parts of Europe. 

 Their numbers must have been very great, 

 as M. Dufresne informed Lamarck that the 

 road from Auxerre to Avalon, in Burgundy, 

 was absolutely paved with them ; and we 

 know that it is no uncommon occurrence 

 to find them used in parts of the west of 

 England to pave the roads. It has been 

 suggested that " these animals must have 

 been very important agents, their carnivo- 

 rous habits duly considered, in keeping the 

 balance among the other tenants of the seas, 

 by preventing the excessive multiplication 

 of Crustacea, as well as of other molluscs, 

 and of fishes." The nearest recent ally of 

 this extinct species is supposed to be the 

 SriBULA [which see]. 



AMPELIIXE. A family of birds called 

 CHATTEKKKS [which see]. 



AMPHIBIA. Steictly speaking, the term 

 Amphibia will apply only to such animals 

 as have the power of living, indifferently, at 

 the same time, either upon land or in water, 

 yet in common conversation we are ac- 

 customed to denominate Seals, Otters, Bea- 

 vers, &c., besides many Reptiles, amphibious, 

 because their organization disposes them to 

 resort either to the land or water for pro- 

 curing food, or whose habits are at once 

 terrestrial and aquatic. But this is by far 

 too comprehensive a sense. Linnaeus applied 

 the term generally to the third class of his 

 system of zoology, which comprised not only 

 all the animals since more properly de- 

 nominated Reptiles, such as the Tortoises, 

 Lizards, Serpents, and Frogs, but likewise the 

 Cartilaginous Fishes. It is now admitted, 

 however, that Linnaeus was not correct in 

 this classification, and that a truly am- 

 phibious animal should possess the extra- 

 ordinary double apparatus (lungs and gills 

 at one and the same time) for extracting 

 the principle which supports animal life in- 

 differently from either element. [See BA- 



TBACHIANS.] 



AMPHIDESMA. A genus of small round 

 or rather oblong Shells, slightly gaping and 

 inequilateral, found in the sand on the sea- 

 coasts of tropical countries, and also those 

 of England, France, &c. The Amphidesma 

 variegatum, described by Lamarck, is a na- 

 tive of the coast of Brazil. " In most bivalve 

 shells," Sowerby observes, " the cartilage 

 and ligament are united in one mass, or 



C laced close to each other ; the contrary 

 i this case gives rise to the name, which 

 signifies double ligament" 



AMPHIOXUS.orLANCELET. A small 

 fish of the Lamprey family. Its form is 

 compressed ; the head pointed, without any 

 trace of eyes ; a delicate membranous dorsal 

 fin extends the whole length of the back j 

 and the tail is pointed. At one time this was 

 regarded as a mollusc, the best known species 

 being the Limax lanceolatus of Pallas. It is 

 found on the coasts of England and Ireland, 

 in the Forth of Clyde, and in the Mediter- 

 ranean. Mr. Gray has described a second 

 species from the Eastern seas (A. Belcher i). 



(J 



