284 THE VOYAGE OF H.M.S. CHALLENGER. 



Exceptionally also simple oeellar organs are found attached to the outer surface of 

 the body and appear as spherical projections. 



The lateral line may be converted into a series of oeellar phosphorescent organs, 

 every one of the scales which cover the lateral slime-canal bearing on its outer surface a 

 phosphorescent organ connected with the tissue below by a central perforation of the 

 scale. 



We have, therefore, the following six kinds of regular oeellar phosphorescent 



organs :- 



1. Kegular oeellar simple phosphorescent organs sunk in the body, without 



pigment coat and without reflector. 



2. Regular oeellar simple phosphorescent organs sunk in the body, with pigment 

 • coat and without reflector. 



3. Regular oeellar composite phosphorescent organs sunk in the body, without 



reflector. 



4. Regular oeellar composite phosphorescent organs sunk in the body, with 



reflector. 



5. Regular oeellar simple phosphorescent organs attached outside to the body. 



6. Regular oeellar organs attached to the difi'erentiated lateral line. 



The irregular glandular phosphorescent organs are always found on the head, and 

 besides, sometimes also on the sides of the body (Astronesthes), on the tail (some species 

 <jf Scopehts, Leydig), and on specially difi'erentiated barbels {Ojiostoinias micripnus, 

 Malacostciis indiciis). 



These have not been taken notice of by Ussow ; they are designated by Leydig as 

 " Leuchtorgane." 



Six kinds of glandular organs are met with : — 



1. Glandular organs scattered irregularly. 



2. Glandular organs on the lower jaw. 



3. Glandular organs on the barbels. 



4. Glandular organs under the gill-cover. 



5. Suborbital, highly difi'erentiated glandular phosphorescent organs without 



reflectors, and 



6. With reflectors. 



These may accordingly be with or without reflectoi-s. A pigment coat is, how- 

 ever, invariably present in all the diff"erent kinds of irregular glandular phosi)horescent 

 organs. 



