of 7 — 9 rays, has been modified into a broad denticulate crest. Neither 

 do the fossil species Argyropelecus logerati Aramb. (Arambourg 1929) 

 and A. hullockii David (David 1943) display any similarities with the 

 material under investigation. 



The remaining (third) igenus Polyipnus Giinther ^ with which we 

 have to deal, apparently comes closest despite a few differences, to the 

 remains here examined, in body shape, structure of fins and, above all 

 in the arrangement of the luminous organs — a character of maximum 

 significance. The satisfactory state of preservation of the luminous 

 organs did, indeed, make possible a comparison in this respect of the 

 fossil and living representatives. Among the several species known in 

 recent fauna, Polyipnus fraseri Fowler (Fowler, 1934) comes nearest 

 to the Sobniow remains in the distribution of the luminous organs. In 

 this species the preanal, anal and subcaudal photophores occur in three 

 groups, similary as in P. sohnioviensis. Another common character is 

 the presence of 10 rays in the dorsal fin, also the lack of paired spines 

 before the first rays of this fin. 



The two species just mentioned differ, however, in fundamental 

 characters, as in shown in Table 4. These differences bar the assignment 

 of the Sobniow forms to P. fraseri Fowler, necessitating the estab- 

 lishment of a new species: Polyipnus sohnioviensis. 



Order Scopeliformes 



Family Myctophidae 



Genus Eomyctophum Danilchenko, 1947 



(Figs. 7—11; PI.III, Fig.2) 



1947. Eomyctophum Danil.; P. G. Danilchenko, Ryby semeistva 

 Myctophidae., p. 193—196 Figs. 1, 2. 



This is the only genus of the Myctophidae represented in the Jaslo 

 shales of Sobniow, and at the same time the dominating form in our 

 collection. It is represented by small fishes with ^vell preserved lumi- 

 nous organs. 



The skull. Viewed from the inside on all specimens. (Fig. 7). The 

 orbit rather large, displaying specific variability, more or less anteriorly 



3 The recent monotypic Snellius Koumans — represented by S. hoschmai 

 Koumans — which was described in 1953, is the 4th genus of the Sternoptychidae. 

 In view of lack of adequate literature, it could not be included by the writer 

 in her comparison of the fossil and recent representatives of this family. 



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