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CAECILIA
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CAECILIA . This name was given by See also:Linnaeus to the See also:blind, or nearly blind, See also:worm-like Batrachians which were formerly associated with the See also:snakes and are now classed as an See also:order under the names of Apoda, Peromela or Gymnophiona. The type of the genus Caecilia is Caecilia tentaculata., a moderately slender See also:species, not unlike a huge See also:earth-worm, growing to 2 ft. in length with a See also:diameter of three-quarters of an See also:inch. It is one of the largest species of the order. Other species of the same genus are very slender in See also:form, as for instance Caeciliai gracilis. which with a length of 24 ft. has a diameter of only a See also:quarter of an inch. One of the most remarkable characters of the genus Caecilia, which it shares with about two-thirds of the known genera of the order, is the presence of thin, See also:cycloid, imbricate scales imbedded in the skin, a See also:character only to be detected by raising the epidermis near the dermal folds, which more or less completely encircle the See also:body. This feature, unique among living Batrachians, is probably directly inherited from the scaly Stegocephalia, a view which is further strengthened by the similarity of structure of these scales in both See also:groups, which the histological investigations of H. See also:Credner have revealed. The See also:skull is well ossified and contains a greater number of bones than occur in any other living Batrachian. There is therefore strong See also:reason for tracing the Caecilians directly from the Stegocephalia, as was the view of T. H. See also:Huxley and of R. Wiedersheim, since supported by H. Gadow and by J. S. See also:Kingsley. E. D. See also:Cope had advocated the abolition of the order Apoda and the See also:incorporation of the Caecilians among the Urodela or Caudata in the vicinity of the Amphiumidae, of which he regarded them as further degraded descendants; and this See also:opinion, which was supported by very feeble and partly erroneous arguments, has unfortunately received the support of the two See also:great authorities, P. and F. See also:Sarasin, to whom we are indebted for our first See also:information on the breeding habits and development of these Batrachians. The knowledge of species of Caecilians has made rapid progress, and we are now acquainted with about fifty, which are referred to twenty-one genera. The See also:principal characters on which these genera are founded reside in the presence or See also:absence of scales, the presence or absence of eyes, the presence of one or of two See also:series of See also:teeth in the See also:lower See also:jaw, the structure of the tentacle (representing the so-called " balancers " of Urodele larvae) on the See also:side of the snout, and the presence or absence of a vacuity between the parietal and squamosal bones of the skull. Of these twenty-one genera six are See also:peculiar to tropical See also:Africa, one to the See also:Seychelles, four to See also:south-eastern See also:Asia, eight to Central and South See also:America, one occurs in both See also:continental Africa and the Seychelles, and one is See also:common to Africa and South America. These Batrachians are found in See also:damp situations, usually in soft mud. The See also:complete development of Ichthyophis glutinosus has been observed in See also:Ceylon by P. and F. Sarasin. The eggs, forming a See also:rosary-like See also:string, are very large, and deposited in a burrow near the See also:water. The See also:female protects them by coiling herself See also:round the See also:egg-See also:mass, which the See also:young do not leave till after the loss of the very large See also:external gills (one on each side); they then See also:lead an aquatic See also:life, and are provided with an opening, or spiraculum, on each side of the See also:neck. In these larvae the See also:head is See also:fish-like, provided with much-See also:developed labial lobes, with the eyes much more distinct than in the perfect See also:animal; the tail, which is quite rudimentary in all Caecilians, is very distinct, strongly compressed, and bordered above and beneath by a dermal See also:fold. In Hypogeophis, a Caecilian from the Seychelles studied by A. Brauer, the development resembles that of Ichthyophis, but there is no aquatic larval See also:stage. The young leaves the egg in the perfect See also:condition, and at once leads a terrestrial life like its parents. In accordance with this abbreviated development, the caudal membranous See also:crest does not exist, and the branchial See also:aperture closes as soon as the external gills disappear. In the South See also:American Typhlonectes, and in the Dermophis from the See also:Island of St See also:Thorne, See also:West Africa, the young are brought forth alive, in the former as larvae with external gills, and in the latter in the perfect See also:air-breathing condition. (G. A. Additional information and CommentsThere are no comments yet for this article.
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