SENSE ORGANS OF AMIURUS. 26$ 



The R. lateralis vagi which supplies the sense organs of the canal is 

 not situated in the subcutaneous tissue beneath the canal, but a little 

 distance inwards between the two masses of muscle, a branch being 

 detached to pass outwards to each nerve-hillock. In transverse 

 sections through the canal, it is obvious that it is situated between 

 the epidermis and the stratified fibrous layer of the corium, being 

 lodged in what is elsewhere the pigmentary layer of the corium, 

 although the pigment is practically absent in the neighbourhood of 

 the canal. The epithelium of the canal which is quite low, except 

 where it is transformed into the neuro-epithelium of the nerve- 

 hillock, is continuous at the pores with the surface epithelium of the 

 skin. An exceedingly delicate connective tissue surrounds the 

 epithelium, separating it from the proper wall of the canal, which is 

 formed in the neighbourhood of the pores of a dense connective 

 tissue whose elements are disposed radially to the wall of the canal,, 

 but in the neighbourhood of the nerve-hillocks, and indeed for the 

 greater part of the canal between the pores, by a much thinner layer 

 of osseous substance, so disposed as to form a complete tube for the 

 greater part of its course, but less complete towards its ends. No 

 bone corpuscles are present in the osseous wall of the canal, as is 

 also noted by Leydig and Bodenstein for the forms described by 

 them. I am unable to identify the above-mentioned dense connec- 

 tive tissue with cartilage as Bodenstein does, the corpuscles are quite 

 similar to connective tissue corpuscles, and there is no matrix stain- 

 ing in Bismarck brown, as is the case even in cartilage which has a 

 minimum of intercellular substance. Separating the dense wall from 

 the surrounding tissues is again a layer of reticular tissue belonging 

 to that which I have above spoken of as the pigmentary layer of the 

 corium. 



The lateral canal of the adult is approximately -2 mm. in transverse 

 diameter ; in young specimens of two inches in length, hardly one- 

 third of that. , 



To study the course of the mucous canals in the head a series- 

 through young forms is most convenient, although approximately the 

 direction of the canals may be seen also from the pores. (Figs. 4,. 

 5, 6.) The pores do not open directly into the canals of the head 

 as they do into that of the lateral line, but by longer or shorter 

 tubes — a circumstance noted also by Bodenstein for Coitus — and con- 



