REPORT ON THE DEEP-SEA FISHES. 177 



vvide, the maxillary extending to the posterior end of the praeoperculum ; lower jaw very 

 prominent in front. The maxillary is armed with a single series of numerous teeth which 

 gradually increase in size towards its posterior extremity ; in the posterior half of the 

 bone some of the teeth (placed at regular intervals) are larger than the others, but the 

 difference between them is much less than in the other species of this genus. Inter- 

 maxillary with one or two larger and several small teeth. Mandibulary teeth extremely 

 numerous and closely set, decreasing in size towards the front ; but near to the 

 symphysis the bone is armed with a single long fang which appears to be easily lost, 

 as it is present only in a few of the specimens ; infraorbital bone not dilated, leaving the 

 whole of the cheek uncovered. Branchiostegals nine. , 



The dorsal fin commences opposite to the origin of the anal, and is as high as the 

 body underneath. Form of the anal as in the other species ; it terminates at a short 

 distance from the caudal, the caudal peduncle being not much longer than deep. Caudal 

 fin forked. Pectoral fin extremely narrow ; ventral fin extending beyond the vent. 



Some of the specimens are still provided with very large and deciduous scales, there 

 being only about five in a vertical series between the origins of the dorsal and anal fins. 

 But in the majority of the specimens the skin is quite scaleless, and does not show even 

 traces of pouches. The colour of all the specimens is black. 



Luminous organs are present as very small eye-like spots ; they are arranged in two 

 series along each side of the abdomen, and in a single series along each side of the tail. 

 The branchiostegal series is likewise present, as well as an organ below the small eye, 

 but the glandular mass on the back of the tail is only rudimentary. 



Photichthys. 



Phosiehthys, Hutton, Cat. New Zeal. Fish., p. 55. 



This genus is closely allied to Gonostoma, from which it differs in the following 

 points : — 



Both jaws are armed with a single series of teeth ; those of the maxillary being 

 small and equal in size. The intermaxillary is armed w4th two large fangs besides the 

 small teeth ; mandible with seven large equidistant teeth, the spaces between them 

 being filled up with very small denticles. Vomer with a fang on each side of its head ; 

 palatine with strong, curved teeth, which gradually decrease in size backwards. The 

 dorsal fin corresponds in position to the space between ventrals and anal ; adipose fin 

 small. Air-bladder present as a long simple sac with thick walls. 



As the specimens available are very much deteriorated, it appeared rather hazardous 

 to enter upon the examination of some points of their anatomical structure. On the 

 whole, it resembles much that of Gonostoma. The stomach is csecal ; when empty, its 



(ZOOL. CHALL. EXP. PART LVII. 1887.) I'll 23 



