256 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



erally considerably more branched and possessing more delicate 

 processes than the pigmentary cells of the corium. 



(h) Non- Epithelial Elements.— Certain small bodies of nuclear 

 appearance are met with frequently in the lower layers of the epider- 

 mis surrounded by a scanty protoplasm. In size the nuclei agree 

 fairly well with those of the amoeboid cells of the connective tissue. 

 It is possible, however, that preparation with suitable methods might 

 indicate the existence of interepithelial nerves, a matter which de- 

 serves investigation since Pfitzner's 1 discovery of the nerve endings 

 in the epidermis of amphibian larvse. 



The following layers are present in the corium of Amiurus which 

 does not appear to present any peculiarities in this respect not met 

 with in other osseous fishes : — 



(a) The pigmentary or papillary layer. 



(b) The stratified fibrous layer. 



(c) The adipose layer, or subcutaneous connective tissue. 



(a) The Pigmentary Layer. — The palisade cells of the epidermis- 

 rest immediately upon a ' basement membrane,' from which in 

 hardened preparations they are readily detached, leaving behind 

 them the membrane with a distinct jagged edge. The teeth of 

 the latter are probably protoplasmic processes serving to connect 

 the cells with the underlying structures similar to the 'intercellu- 

 lar bridges ' of protoplasm of the higher cells. In the reticular 

 connective tissue which follows the basement membrane are found 

 the vessels and nerves destined for the supply of the epidermis. 

 The pigment cells which are so abundant here are very different 

 in form from the interepithelial pigment cells (Fig. 1) ; they are 

 much larger and have short lobate processes rarely connected 

 in the adult with those of neighbouring cells. This layer would 

 not deserve exclusively the name of pigmentary layer in young 

 forms, where I find a second almost equally strong layer below the- 

 stratified fibrous layer, which disappears, however, in the adult with 

 the exception of a few scattered cells. 



As the papillae vaiy much in number in different regions of the 

 body the papillary layer is necessarily modified by its projection into 

 these structures which contain exactly the same elements, and are- 



iMorph. Jahr. VII. 726. 



