gilbert: the lantern-fishes of japan 75 



line just in advance of vertical from third ventral, the second behind that from 

 fourth ventral. The antero-anals are slightly curved, the anterior spot a little 

 nearer the base of the anal fin. Posterolateral close under the lateral line, 

 vertically over the last antero-anal. Only the first postero-anal over the last anal 

 rays. In thirteen specimens, the combinations found have been as follows: 



7 + 5 in 2 cases, 7 + 7 in 3 cases, 



7 + 6 in 14 cases, 8 + 5 in 3 cases, 



8 + 6 in 4 cases. 



The number is thus seen to agree with the range in D. spinosus. The pre- 

 caudals are also similar, placed at a slight angle and a little farther apart than 

 the spots of the anal series. 



The scales develop serrations in extreme youth; well-developed spines are 

 present in individuals 25 mm. long. As in D. spinosus, the luminous plates 

 develop late. No trace of them is to be found in specimens 65 mm. long. In 

 a male 85 mm. long, there are five overlapping luminous scales on the dorsal side 

 of the caudal peduncle, and in a female 100 mm. long, there is a single plate 

 below. 



Specimens were obtained along the southern and eastern coasts of Japan, 

 at the surface, from the vicinity of Nagasaki to Matsushima Bay. 



Lists of Stations. 



4909. 31° 38' 30" N., 129° 27' 30" E. Intermediate net, 300 fathoms. 



4910. 31° 37' 40" N., 129° 26' 00" E. Surface. 

 4921. 30° 23' 30" N., 129° 36' 30" E. Surface. 

 4973. 33° 24' 15" N., 135° 30' 30" E. 600 fathoms. 

 5052. 37° 57' 45" N., 142° 04' 00" E. Surface. 

 5081. 34° 14' 00" N., 138° 05' 00" E. Surface. 



At Stations 4909 and 4973 the fish probably entered the open net near the 



surface. 



Genus Myctophum Rafinesque. 



{Scopelus Cuvier.) " 



Key to Japanese Species of Myctophum. 



a. No photophores above the lateral line. 



b. Supra-anal photophores in an oblique row. 



c. Second ventral photophore not out of line with the others.. Postero-anals 5 to 7 in 



number M. aflSne. 



cc. Second ventral photophore more elevated than the others. Postero-anals 2 or 3 in 

 number M. latematum. 



