FISHES OF HAWAIIAN ISLANDS. 
591 
they extend well beyond the anal base; in the cotype, to the base of the last ray; third ventral ray 
divided, its outer half produced and modified much as in the outer rays; distance from vent to anal fin 
1.7 in distance from insertion of ventrals. 
Color brownish black, the pectoral filaments and tips of outer ventral rays white; mouth and 
gill-cavities and the peritoneum blackish. 
The co type is 200 mm. long, and was taken at station 4181, vicinity of Kauai, depth 1,000 to 1,314 
fathoms. 
Family MYCTOPHIMt. 
Nannobrachium nigrum Gunther. 
Three small specimens in rather poor condition, having lost much of the integument, agree closely 
with Gunther’s description and figure. Dorsal 14; anal 16 or 17; gill-rakers 18 on outer arch; eye 
somewhat larger in our specimens, a trifle less than 5 rather than 4 in head, longer than snout, and 
exceeding also the longest gill-raker. While we do not venture to distinguish the Hawaiian form on 
the basis of the larger eye, there may exist other characters not given by Gunther. The number and 
distribution of the luminous spots in the type of N. nigrum remain wholly unknown. In the Hawaiian 
specimens, these are arranged as follows: Mandibulars, 3 pairs, very inconspicuous; operculars, but 1 
pair evident, poorly developed; pectorals, 4 pairs, 1 immediately below lateral line, 1 on pectoral base, 
1 vertically below pectoral base and halfway to median line, 1 on line between pectoral base and first 
thoracic pair; thoracics, 5 pairs, the fourth pair high up on sides, over interspace between third and fifth 
pairs, the lower pairs evenly spaced; supraventrals, 1 pair, immediately below lateral line; ventrals, 4 
pairs, evenly spaced; supra-anals, 3 pairs, 2 forming an oblique line upward and backward from vent, the 
uppermost on the lateral line, the third well forward, over the interspace between second and third 
ventrals, on a level with the fourth pair of thoracics; anals in 2 well-separated series, the anterior 
group with 6 pairs, of which the first 5 are in parallel lines, the sixth placed high, in a line joining the 
fifth anal and the posterolateral; posterior series also with 6 pairs; posterolaterals, 1 pair, on the 
lateral line; caudals 4, the anterior 3 forming a right-angled or obtuse-angled triangle at base of lower 
lobe, the fourth separated from the third by a wide interspace, placed on, or even a little above, the 
end of the lateral line; a luminous streak above and one below on caudal peduncle. 
In size and position of fins and in the arrangement of the photophores N. nigrum shows great 
resemblance to the type of Lampanyctus, L. crocodilus (Risso). The 2 genera are distinguished only 
by the reduction of the pectorals in Nannobrachium, a character of doubtful value. The pectorals are 
narrow in our specimens, and consist of a few (3 to 6) short rays. The body is uniformly black, the 
fins black on basal portions. 
The species was taken at the following stations: No. 4108, Kaiwi Channel, 411 to 442 fathoms; 
4110, Kaiwi Channel, 449 to 460 fathoms. The type of N. nigrum was taken south of the Philippine 
Islands, at a depth of 500 fathoms. 
Nannobrachium nigrum Gunther, Deep-sea Fishes, Challenger, 1887, 199, pi. 52, fig. B, south of the Philippines. 
KEY TO HAWAIIAN SPECIES OF DIAPHUS. 
a. No luminous areas about eye urolampus, p. 591 
aa. Luminous area covering entire snout chrysorhynchus, p. 592 
aaa. A narrow luminous streak above eye and one below it adenomus, p. 592 
Diaphus urolampus Gilbert & Cramer. 
One specimen from station 4016, vicinity of Kauai Island, depth 305 to 318 fathoms. The types 
were from 295 and 310 fathoms. 
The species has the following characteristic disposition of the photophores: Upper pectorals 
immediately below lateral line, the supraventrals, upper supra-anals, and posterolaterals in contact with 
the lateral line; the fourth thoracics high on sides, on a level with pectoral base; second and third 
ventrals elevated, on the same level, a little above ventral base; supra-anals 2, forming a slightly 
oblique line which traverses the fifth ventrals; first anal (interpreted as one of the supra-anals in the 
description cited below) elevated, nearly vertically above the second; the second to sixth anals forming 
F. C. B. 1903, Ft. 2—2 
