MISCELLANEOUS. 263 



tion ; and the existence of the parasite is apparently dependent on the 

 existence of the life of the other. If the one dies, so shall the parasite 

 be destroyed. 



The subject of this paragraph infests the gills of the ling, to which 

 it adheres with considerable tenacity. 



It is of a thin and flattened form, extending nine lines in extreme 

 length, by about two in the broadest part. One extremity dilates into two 

 portions, to the right and left, each composed of four tentacular-looking 

 organs, a line in length. The remainder of the body tapers downwards, 

 much like that of the common Planarise. A longitudinal internal cavity 

 seems to consist of a larger and a smaller compartment ; besides which, 

 numerous pinnate organs also occupy the substance of the body. The 

 colour of the whole is bluish-grey. 



The body being remarkably thin, soft, and flexible, it applies closely 

 to its site, with some adhesion ; and the two anterior portions clasp the 

 rib of the gills in their fold. 



They have little other motion than slightly extending and con- 

 tracting. 



Probably the tentacula are hollow. 



The site of the mouth could not be discovered ; but a ventral pore 

 was visible after death. Can this be the orifice of a proboscis ? 



In a short time these animals lose the anterior portion by decays 



On one occasion, twenty-nine specimens, of various dimensions, were 

 removed from a portion of the gills of a ling ; and several were found on 

 other occasions. 



It is doubtful whether their survivance is- not very short, on 

 removal. 



PLATE XXXVI. 



FIG. 1. Octodactylus inhasrens. 

 2. The same, enlarged. 



