CEPHALOPODS. 323 



secretions of the other accessary organs to good digestion, 

 Sir E. Home believes that the inky fluid is intended also 

 to have some effect upon the lower portion of the intes- 

 tinal canal, to enable this to extract from its contents " a 

 secondary kind of nourishment,"* an opinion not very 

 probable in itself, and with but a few fanciful analogies in 

 its support. 



* Comp. Anat. i. 369 and 393. 



*.* Troschel and, more particularly, M. Lbven, have sought in the form 

 and various armature of the tongue of the Cephalophorous mollusca (viz., 

 Cephalopoda, Pteropoda, and Gasteropoda), a character on which to distin- 

 guish their natural alliances and affinities. The researches of Lbven into 

 this subject seem to have been extensive, and are very interesting ; but I 

 am only acquainted with them through the medium of an imperfect trans- 

 lation, with the perusal of which I was favoured by Mr. Alder of Newcastle. 

 Hence, I cannot presume to offer the results, at which Lbven has arrived, to 

 the student. 



