THRKAD-CKI.LS ANO EPlDI'^UMf'^ OK MYXINK. 355 



The Thread-cells and Epidkrmis 0/ Myxine. By J. E, 

 Blomfield, B.A. (With Plato XXX.) 



The observations here recorded were begun some years 

 ago by the advice and with the supervision of Professor 

 Lankestcr in the Botanical Gardens at Oxford, and by his 

 kindness in supplying me with specimens and the use of the 

 Zootomical Laboratories of University College, Loudon, I 

 have been enabled to verify and extend them. 



The epidermis of the various Cyclostomes has been the 

 object of researches by several different observers, but the 

 most exhaustive account is contained in a paper by M. 

 Alexandre Foettinger, which appeared in March, 1876, in the 

 ' Bull, de I'Academie royale de Belgique,' 2me seiie, Ix, 

 No. 3. This thesis embodies the results of former writers, 

 and gives a very complete account of the epidermis as seen 

 in Petromyzon fiumatilis and P. planeri and the larval con- 

 dition of Ammocoete. And since this description will serve 

 us as a standard of comparison for the similar structures in 

 Myxine, it will be necessary to give a short account of his 

 researches before entering on the immediate subject of this 

 paper. 



The epidermis of Petromyzon is composed of a series of 

 cells, of which M. Foettinger recognises four chief varieties : 

 The ordinary epidermic cells. 

 The caliciform or goblet cells. 

 The club cells. 

 The granular cells. 



The ordinary epidermic cells, arranged in series and press- 

 ing one against the other, form the major part of the epider- 

 mis. They possess a nucleus, and in the lower strata very often 

 two nuclei. Their shape varies according to the situation in 

 which they are found. In the deeper layers — that is, those 

 next the dermis, they are prismatic or stalked, resting on 

 an expanded base, and in the more superficial region the 

 external series of cells has its free border thickened and 

 perforated by fine pore canals. 



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