185 



AMPHIBOLE. 



AMPHISB^ENA. 



188 



produce the conviction that Chirotherian and Labyrinthodontic foot- 

 impressiona are identical ; and that Afastodunsaurus, Salamandroide, 

 Phytosaurui, Chirotherium, and Labyrinthodon are one and the same 

 genus, which ought for the future to be designated by the last- 

 mentioned name. We owe this evidence principally to the use of the 

 microscope in skilful and judicious hands ; and it is impossible not 

 to be struck with the wonderful applicability of that instrument to 

 the largest of created bodies as well as to the smallest, when we look 

 at the results of Professor Owen's discovery of the highly-organised 

 dental structure in Labyrinthodon, an extinct animal of a low grade, 

 where it could hardly have been expected to occur. 



The reading of Professor Owen's memoir was accompanied by 

 the exhibition of a diagram representing a restoration of two species 

 of Labyrinthodon. By the Professor's kindness, we have been enabled 

 to give a greatly reduced copy of one of them. [See the preceding 

 column.] The bones which appear within the outline are those which 

 were known when the paper was read. The animal is represented as 

 impressing its footsteps on a shore of sand, now New Red-Sandstone. 

 There is reason for believing that this Batrachian was not smooth 

 externally, but was protected, on certain parts at least, by bony scutella. 



Specimens of the foot-prints may be seen in the British Museum 

 and in that of the Royal College of Surgeons in London. 



AMPHIBOLE, a mineral belonging to the group of silicates of 

 magnesia, lime, iron, and manganese. [AnoiTE.] 



AMPHIBOLI'TE, a name sometimes given to the simple mineral 

 more commonly called Hornblende, and which was introduced by 

 Haiiy, the mineralogist, who uselessly changed many names. He 

 called Hornblende Amphibole, because it is easily mistaken for Augite, 

 another simple mineral closely allied to it in composition, from 

 du(fi/3oAos, equivocal. 



AMPHIDESMA, a genus of Marine Bivalve Shells, which are found 

 in the sand on the sea-coast of tropical climates. The shells are oval 

 or rounded, sometimes rather twisted and slightly gaping behind. 

 They have two hinge teeth in each valve, and often distinct com- 

 pressed lateral ones. The elastic cartilage ia placed in a small 

 triangular cavity just behind the hinge teeth. The animals of these 

 shells are unknown ; but they are supposed to have long syphons, 

 like the Tellens, as the shells have a broad deep inflation on the back 

 edge of the submarginal scar, formed by the attachment of the 

 muscles which retract these syphons, as in the Tellens, from which 

 genus it simply differs in the position of its cartilage. 



Lamarck gave the name of Am/i/iidesma to this genus, because he 

 observed that it had a ligament and a cartilage, which he regarded as 

 peculiar to this genus, he having, like the rest of the zoologists before 

 the appearance of the Conchological Observations in the ' Zoological 

 'Journal,' considered what is usually called the ligament of bivalves as 

 only one substance. It is however two substances, of very different 

 structure and use ; the outer, or ligament, being inelastic, and only 

 employed to keep the two valves together, is formed of fibres 

 extending from the edge of one valve to the other ; but the cartilage 

 is elastic, and formed of perpendicular fibres, like the prismatic 

 crystalline-structured shell, its use being to separate the valves from 

 one another when the muscles which keep them closed are relaxed. 

 When the valves are closed, this part is compressed by their edge. 

 For this purpose it is sometimes, as in the shell under consideration, 

 placed in a small triangular cavity close to the hinge, when the shell 

 is said to have an internal cartilage, the ligament being still in its 

 usual place. In other shells it is placed, along with the ligament, on 

 the margin f flie valves, and is pressed, when the valves are closed, 

 against the ligament itself, which forms its outer wall. The resist- 

 ance which the ligament offers is the means of opening the shell. The 

 cartilage has opaline reflections, and the cartilages of some large shells, 

 as the mother-of-pearl shells, are sold by the jewellers under the name 

 of Peacock-Stone, or Black Opals. They are not so much used now 

 as formerly, but they are still much sought after on the Continent, 

 especially in Portugal. 



II'DETUS, a genus of Echinidir, found in the Crag of Suffolk. 



AMPHIGENE, a mineral abundant in the lava of Vesuvius, con- 

 sisting of silica, alumina, and potash. [LsuciTE.] 



AMPHPON (Pander), a genus of Fossil Crustacea (Trilobitu), four 

 species of which have been described, from Tyrone and Watetford-lby 

 Colonel Portlock. 



AMPHIOXUS. [BRANCHIOSTOMATA 1 



AMPHIKOA. [ACAI.EI-H.*:.] 



AMPHISB^ENA (from i^io-^oii/o, which signifies 'an animal that 

 can walk in both directions ' ), a genus of Serpents, distinguished by 

 their bodies having nearly the same uniform thickness from the head 

 to the extremity of the tail, by their small mouths and extremely 

 diminutive eyes, their remarkably short tails, and the numerous rings 

 of small square scales which completely surround this organ and toe 

 body. A range of small pores runs in front of the vent, which is 

 situated nearly at the end of the tail ; the jaws alone are provided with 

 a single row of small conical teeth, the palate being without any ; and 

 even these of the jaws are few and distant from one another. They 

 are moreover destitute of fangs, and are consequently harmless and 

 inoffensive, living for the most part ujion ants and other small insects, 

 and inhabiting ant-hills and burrows which they themselves construct 

 under ground. The nature of their food does not require these animals 



to possess the power of dilating the mouth and gullet to the extraordi- 

 nary extent that is observed in the boas, pythons, and other serpents in 

 general, which live for the most part upon animals proportionally much 

 larger than themselves, and in order to admit the huge mouthful have 

 the upper and under jaws both equally moveable xipon the cranium. 

 In the Amphwbcena, on the contrary, the upper jaw is fixed to the 

 skull and intermaxillary bones, as in birds and mammals, so that the 

 head remains constantly in the same plane with the body a form 

 which permits the animal to move equally well either backwards or 

 forwards, and which has acquired for it the name by which it is 

 distinguished. 



The head of the Amphisbana is so small, and the tail so thick and 

 short, that it is difficult at first sight to distinguish one from the other, 

 and this circumstance, united to the animal's habit of proceeding either 

 backwards or forwards as the occasion may require, has given rise to 

 the popular belief very generally spread throughout Brazil and other 

 parts of South America, the native countries of this genus, that it 

 possesses two heads, one at each extremity, and that it is impossible 

 to destroy the animal by simple cutting, as the two heads mutually 

 seek one another in ease of such a serious accident, and soon re-unite 

 as if nothing had happened. Ignorance is the parent of superstition 

 and absurdity, and one wonder naturally produces twenty. It is not 

 therefore surprising that, among an ignorant and credulous people, the 

 singularity of the Amphisbcena' s form and habits should have given 

 rise to this and a multitude of other gross fictions. " Another snake," 

 says Stedman, in his ' History of Surinam,' " which I also observed 

 here, is about 3 feet long, and annulated with different colours ; it is 

 called Amp/iiibrfna, from the supposition of its having two heads; 

 and the truth is, that from its cylindrical form the head and tail BO 

 much resemble each other that the error is almost pardonable ; besides 

 which, the eyes are nearly imperceptible. This is the snake which, 

 being supposed blind, and vulgularly said to be fed by the large ants 

 already described, is in this country honoured with the name of King 

 of the Emmets. The flesh of the A mpkitbana, dried and reduced to 

 a fine powder, is confidently administered as a sovereign and infallible 

 remedy in all cases of dislocation and broken bones ; it being very 

 naturally inferred that an animal which has the power of healing an 

 entire amputation in his own case, should at least be able to cure a 

 simple fracture in the case of another." Two centuries have scarcely 

 passed since opinions equally credulous and absurd were universally 

 prevalent among the most enlightened nations of Europe, when grave 

 and learned physicians administered the bezoar or rhinoceros" horn 

 with as much confidence as the simple Brazilian at the present does the 

 powdered flesh of the AmphMfena. 



The gcmm Amphiib(fna, as at present defined, contains only American 

 species, which are confined to Brazil, Surinam, and other tropical parts 

 ,of the Continent. Of these the following are the principal : 



1. The A.fMliyinosa, the first and still the best-known species of 

 the whole .genus, is, like all the other Amphisbsenas, confined to the 

 hotter regions of South America, and does not inhabit Ceylon or any 

 other part of the East Indies, as Linnseus and Lace'pede have errone- 

 ously supposed, and asserted on the authority of Seba. The general 

 colour of this serpent is a deep brown, varied with shades of white, 

 more or less intense according to the difference of the individual and 

 the season of casting the old and acquiring the new external skin. It 



/.in iilii-.hu an fulighioia. 



grows to the length of 18 inches or 2 feet, of which, however, the tail 

 measures only 1 inch or 15 lines. The body is surrounded by upwands 

 of 200 rings, and the tail by 25 or 30 ; the eyes are covered and almost 

 concealed by a membrane, which, added to their naturally diminutive 



