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XXV. — Observations on the Anatomy of the Skin of a Species 

 of Murana. By Andrew Clark, M.D. Communicated by 

 J. E. Gray, Esq. 



(Read March 29, 1848). 



The following anatomical details are based chiefly on examinations 

 of the skin of a species of Murana ; but as the skins of several allied 

 species were likewise examined, and as the points of difference were 

 few and of degree only, the present account of the anatomy of the 

 skin may, in as far as it extends, be considered typical of such mem- 

 bers of the eel tribe as are devoid of dermal appendages in the form of 

 bones or scales. 



The thickness of the skin in these animals, its density, and the pre- 

 sence of much oily matter, render any minute examination of it ex- 

 tremely difficult. By macerating the skin, however, sometimes in 

 ammonia, sometimes in ether or potass, these difficulties were greatly 

 lessened, and the study of its histological elements rendered compa- 

 ratively easy. 



The skin of the Murana may, in a philosophical sense, be 

 considered a mediate phase of compound textural development, con- 

 necting the mucous membrane on the one hand with the less highly 

 organized tegumentary membrane on the other, and affording an illus- 

 tration of one of the many gradations of form by which these struc- 

 tures merge into each other. 



The only essential elements in the composition of the mucous tis- 

 sue in its most comprehensive signification are the primary, germinal, 

 or basement membrane, and the layer or layers of epithelial cells on 

 its free surface, the conjoint inflections of which constitute the 

 follicles or glands. 



These elements undergo various modifications, and receive also 

 certain appendages, according to the position in which the tissue is 

 found and the particular end which it is destined to fulfil in the 

 economy. 



To the primary membrane and its epithelium are added on its deep 

 surface various forms of areolar tissue and capillaries ; and, with the 



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