The anal fin always occurs behind the dorsal fin. The distance 

 between the last ray of the dorsal fin and the first ray of the anal fin, 

 as expressed by number of vertebrae, is an index character of a specif- 

 ic kind; in the material here under investigation, it ranges from to 4 

 vertebrae, while according to Danilchenko (1947) in Eomyctophum 

 vienneri Danil. it is even represented by 5 vertebrae. The number of 

 rays in the anal fin has no systematic significance; these rays are 

 thinner than those of the dorsal fin, their number ranjges from 12 to 13. 

 The interhaemalia are extremely thin; the first are the longest, the 

 subsequent ones are gradually reduced, and in number they are always 

 by one fewer than the rays. The first rays are the longest (though 

 shorter than the longest rays of the dorsal fin), these following are 

 gradually shorter. According to Danilchenko (1947), species from the 

 Caucasus had an adipose fin whose contours have not been observed 

 on the present writer's material. 



The caudal fin is rather long, deeply notched, each lobe consisting 

 of 9 — 10 cardinal rays and of 4 — 5 shorter side rays (Fig. 9). 



The luminous organs have been preserved on our material as large 

 black stains of pigment on the head, the precaudal and the caudal areas. 

 The most idistinct among them are the anal organs (AO) and the pre- 

 caudal photophores (pre.) *. The investigation of numerous individuals 

 from the genus Eomyctophum Danil. has shown the arrangement of 

 the photophores to be the same on all these specimens, irrespective 

 of species (Fig. 9), though their state of preservation varies so much 

 that at first sight it suggests the semblance of a strongly variable 

 arrangement of such photophores. In the first place, those most sat- 

 isfactorily preserved have a characteristically crescent shape (Fig. 9), 

 while in many individuals a single photophore gives the impression of 

 two separate stains of pigment. However, a more detailed inspection 

 of several dozen individuals shows that the two stains are the remains 

 of one large photophore. This supposition is confirmed by the dis- 

 covery of specimens on which two clearly outlined small stains of 

 pigment are seen to be connected by a less distinctly pigmented area 

 (Fig. 10). The two stains result when connected, in a characteristically 

 semilunar shape. Additional evidence in support of the above inter- 

 pretation is that the number of the ,, large" photophores is always equal 

 to double the number of the „smaH" ones. 



* The names and symbols for the particular groups of luminous organs 

 within the Myctophidae are given after Parr (1929). 



2e 



