566 Prof. R. Burckliardt on the 



cluster is slightly removed towards the snout and more 

 reduced than that of L. rostratus. I met with some scattered 

 organs on the anterior dorsal fin itself and also above the 

 foremost gill-opening, while the supralateral row does not 

 extend beyond the posterior dorsal. 



With regard to these organs in Lcemargus brevipennis, I 

 was able, from a specimen in the Paris collection, to prove 

 their presence in this species, and to state the fact that they 

 have a general resemblance to those of L. borealis. It is 

 quite probable that luminous organs are functional in the 

 majority of the Lsemargidse, but possibly so in the young only 

 of the two larger species, in which they most likely have 

 escaped observation. 



It is to the authentication in Isistius brasiliensis of these 

 organs, however, that I attach particular value. 



Here, as in Spinax pusillus, similar conditions obtained 

 for the non- uniformity of these structures in the different 

 specimens which I consulted. For instance, while they 

 could be seen plainly enough in some of them, in others, 

 whose state of perfection previous to their preservation 

 was probably impaired, absolutely no traces of them were 

 perceptible. 



I found their expansion in perfect accord with Bennett's 

 statements concerning this species, who had studied its 

 sphere of luminosity. In place of the non-luminous portion 

 referred to by this author a yellowish-coloured zone was even 

 yet visible on the old spirit-specimen, having its origin above 

 the gill-openings in a breadth of about 1 centim., and widening 

 out ventrally to one of about 2 centim. The zone lying in 

 our figure between the dotted lines contained not a single one 

 of these organs, whilst just behind it the whole of the 

 ventral surface is densely beset with them, though they are 

 more widely dispersed towards the back. 



Some isolated organs can nevertheless also be found scattered 

 along the back. In addition to those mentioned above, they 

 further occur on both dorsal fins. On the top of the head they 

 are equally as scarce as on the back of the body, reappearing, 

 however, in somewhat greater numbers dorsally of the poste- 

 rior angle of the eyes, below the eyes, on the spiraculum, in 

 the angle of the mouth, on the cheeks, and also on the rostrum. 



In regard to number these organs stand to the scales in the 

 ratio of about four of the former to one of the latter on the 

 abdomen, as against one to every ten scales on the upperside. 



Euprotomicrus Labordii is only slightly longer than 

 Isistius, but considerably darker in colour. Its luminous 

 organs are more strongly pigmented and recall to mind rather 

 those of Spinax — though present only on the ventral side, 

 where they are densely massed and quite equally distributed, 



