EEPORT ON THE DEEP-SEA FISHES. XXIX 



families Sternoptycliidse and Scopelidae only, viz., Gonostoma {Gonostoma denudatum), 

 Argi/)'02:>elecus, Sternoptyx, Polyipnus, Photichthys, Scopelus and Nannobrachium. 



5. More or less diflfuse patches of a white glandular substance of varying thickness 

 are found. 



a. On the side of the trunk in Astronesthes. 



h. On the dorsal or ventral sides of the caudal peduncle in Gonostoma and Nanno- 

 hrachium. 



c. On or near the clavicle and more or less within the gill-cavit}- in Steimoptyx, 



Opostomias and Hcdosaurus. 



d. Above the maxillary in the infraorbital region in Gonostoma and Photichthys. 



e. On the top of the snout or in front of the eye in species of Melamiihaes, 



Melanonus and Scopelus. 



f. On barbels in Linophryne, Stomias, Opostomias and Idiacanthus. 



g. On fin rays in Melanocetus, Chaunax, and Himantolophus reinhardtii. 



6. In this group these large glandular masses are differentiated, forming a rounded, 

 more or less oval mass lodged in a cavity of the infraorbital region (as in 5, d), viz., in 

 Anomalops, Echiostoma, Opostomias, Pachystomias, Photonectes, Malacosteus, Idia- 

 canthus, Astronesthes. 



7. Tlie luminous apparatus of the dorsal fin is difi"erentiated, representing a cavity 

 with an aperture from which a tentacle or filament may be exserted. This form is found 

 in Pediculates only, such as Himantolophus, Aegseonichthys, some species of Ceratias, 

 Oneirodes and Linophryne. 



8. The luminous organs of Halosaunis diff"er from all those enumerated, inasmuch 

 as they are arranged on the body in a single series which is lodged on the scales of the 

 lateral line ; on the head they follow the lower branches of the muciferous canals ; in 

 fact, they are situated in them. The organs have also a peculiar diamond-shape, and 

 nearly all lie below, Init free from, the .semitransparent integument of the bodv. 



9. The cephalic organ of Ipnops, the genetic relations of which are still obscure, 

 althouiih there can be no doubt as to its function. 



The disposition of all these organs will be more fully noticed in the following pages, 

 and a complete account of the histology of the more important forms will be given 

 by Professor Moseley and Dr. von Lendenfeld in the Appendices at the end of the 

 Report. 



Light-producing organs are very generally distributed in the abyssal fauna, and those 

 parts of the depths of the ocean in which phosphorescent animals are abundant must be 

 sutticiently illuminated to enable such of them as are provided with well-developed eyes 

 to perceive objects with as much distinctness as do the pelagic forms which sport 

 at the surface at night, and are dependent on the light of the moon and stars and 

 the general phosphorescent light around them. There is no doubt that fishes contribute 



