A M M 



[12 ] 



AMP 



the genera Ammonites, Ammonoceras, 

 Baculites, Turrilites. 



A'MMONITE. (from Jupiter Ammon.) An 

 extinct and very numerous genus of the 

 order of molluscous animals called Cepha- 

 lopoda, allied to the modern genus Nau- 

 tilus, which inhabited a chambered shell, 

 curved like a coiled snake. Species of it 

 are found in all geological periods of the 

 secondary strata ; but they have not been 

 seen in the tertiary beds. They are 

 named from their resemblance to the 

 horns on the statues of Jupiter Ammon. 

 Lyell. 



The ammonite differs greatly from the 

 chambered nautilus, the whorls, or turns, 

 being all distinct, and in the same plane, 

 and the cells very small. The family of 

 ammonites extends through the entire 

 series of the fossiliferous formations, from 

 the transition strata to the chalk inclu- 

 sive. M. Brochant, in his translation of 

 De la Beche's Manual of Geology, enu- 

 merates 270 species ; these species differ 

 according to the age of the strata in 

 which they are found, and vary in size 

 from a line to more than four feet in dia- 

 meter. The geographical distribution of 

 ammonites in the ancient world, seems 

 to have partaken of that universality, we 

 find so common in the animals and vege- 

 tables of a former condition of our globe, 

 and which differs so remarkably from the 

 varied distribution that prevails among 

 existing forms of organic life. We find 

 the same genera, and, in a few cases, the 

 same species of ammonites, in strata, appa- 

 rently of the same age, not only through- 

 out Europe, but also in distant regions of 

 Asia, and of North and South America. 

 Dr. Gerard has found at the elevation of 

 16,OCO feet in the Himalaya Mountains, 

 species of ammonites, identical with those 

 of the lias at Whitby and Lyme Regis. 

 The ammonite, like the nautilus, is com- 

 posed of three essential parts : 1st. An 

 external shell, usually of a flat discoidal 

 form, and having its surface strengthened 

 and ornamented with ribs. 2nd. A series 

 of internal air chambers, formed by trans- 

 verse plates, intersecting the inner por- 

 tion of the shell. 3rd. A siphuncle, or 

 pipe, commencing at the bottom of the 

 outer chamber, and thence passing through 

 the entire series of air chambers to the 

 innermost extremity of the shell. The 

 most decided distinction between ammo- 

 nites and nautili is founded on the situa- 

 tion of the siphon. In the ammonite 

 this organ is always on the back of the 

 shell, but never so in the nautilus. 

 Buckland. 



The opinions of geologists and concho- 

 logists have greatly varied as to the 

 situation and use of the shell of the am- 



monite ; Cuvier, Lamarck, Bakewell, and 

 others, have supposed that the shell was 

 an internal one, but the reasoning of 

 Buckland on this subject, seems conclu- 

 sively and indisputably to prove, that the 

 shell was external. 



AMMONITI'FEROUS. Containing the re- 

 mains of ammonites. 



AMMONO'CERAS. } (from ammon, and 



AMMONOCE'RATITES. $ Kfpag, Gr.) The 

 shells of this genus resemble ammonites 

 in their internal structure, but that they 

 are only curved instead of being spirally 

 convolute. 



AMO'RPHOUS. (from a, priv. and i*op<pjj, 

 form, Gr.) Bodies devoid of shape or form. 



A'MPELITE. (from a/tTreXof, Gr. a vine.) 

 A kind of aluminous slate, belonging to 

 both the fossiliferous and metamorphic 

 series of rocks. 



AMPHI'BIA. (from o/i$t and /3<Y,c, Gr.) 

 A class of animals possessing the property 

 of living either in the water or on dry 

 land. In the Linnaean system the am- 

 phibia form the third class of animals. 

 The lungs of the amphibia differ greatly 

 from those of animals of the classes aves 

 and mammalia. Their body 4s covered 

 with a shell, or with scales, or is quite 

 naked. They have neither hair, mam- 

 mae, feathers, nor radiated fins : they are 

 oviparous or viviparous, and are divided 

 into reptiles and serpents ; or reptilia 

 pedata, and serpentes apodes, the former 

 being furnished with teeth, and the latter 

 being destitute of them. The class Am- 

 phibia, according to Gmelin, consists of 

 two orders ; the first, or Reptilia pedata, 

 being divided into four genera, having 

 generally four, seldom two feet, namely, 

 Testudo, Draco, Rana, and Lacerta. 

 2nd, Serpentia, or serpentes apodes, hav- 

 ing no feet. Some are ovo- viviparous, 

 having the egg hatched in the oviduct. 

 This order is divided into six genera, 

 namely, Crotalus, or Rattle-snake, Boa, 

 huge serpents of Asia and Africa, Coluber 

 or viper, Anguis or blind worm, Am- 

 phisbsena, and Csecilia. Many of the 

 amphibia possess the extraordinary pro- 

 perty of reproducing parts, such as their 

 legs, tails, &c., if destroyed. 



AMPHIBIO'LITHI. (from afi^ifSioQ and 

 XiQog, Gr.) Fossil amphibise. The am- 

 phibiolithi form a very large and important 

 class of fossils. 



AMPHI'BIOUS. (n/i0i'/3io, Gr. amphibie, 

 Fr. anfibo, It.) That partakes of two 

 natures, being able to live either in the 

 air or in the water. 



AMPHI'BIOUSNESS. The quality of being 

 able to live in two elements, air and 

 water. 



A'MPHIBOLE. (a/j0i'/3o\oc, Gr.) The 

 name given by Haiiy, and the French, to 



