ICHTHYOLOGICAL COLLECTIONS 
OF THE ALBATROSS. 399 
Pamily MYCTOPHIDA. The Lantern Fishes. 
‘To. Diaphus theta Figenmann & Kigenmann. 
: Proc. U. 8. Nat. Mus. 1890, 52. 
Five specimens from station 3348, taken off the coast of California near Point 
Arena, Humboldt County, at a depth of 455 fathoms. These are identical with the 
types of M, protoculus, and are in sufficiently good state of preservation to show the 
‘division of the luminous spots, a character not visible in the types of M. protoculus. 
It is obvious that the spots are divided into upper and lower halves, which are 
structurally different, the narrow pigment band indicating this separation on the 
surface. The species is now known from the above locality, from Albatross station 
3072 (off the coast of Washington, 584 fathoms), and from the mouths of Sebastodes 
caught near San Diego, Cal. 
_ The specimens before us show great variation in the size of the subocular 
luminous blotch, and indicate how little dependence can be placed on this as a 
specific character. In addition to the roundish supra-nasal spot described by Eigen- 
‘mann, the species possesses a more or less developed subocular bar. In one specimen 
the latter is a bare line with a minute point separated from it posteriorly. In others 
it is wider, in extreme specimens reaching one-third the diameter of the pupil. There 
Temains constantly separated from it the small dot already referred to. A peculiar 
‘soft flattish body, half as large as pupil, is attached by one edge to the shoulder 
‘girdle just above the insertion of the pectoral fin, the other edge remaining free. It 
is constantly present and uniform in position in all specimens that have come under 
our observation, including types of D. theta and M. protoculus. It may be a luminous 
organ, though it has not strikingly the appearance of one, and its nature must be 
considered problematical. ; 
Myclophum protoculus Gilbert. 
{11. Nannobrachium lJeucopsarum Higenmann. 
Numerous specimens from Alaskan waters agree entirely with those from the type 
locality. ‘l'wo very closely related species are found among these northern speci- 
mens, and both are also present in the dredgings from the Santa Barbara Channel. 
Both of these are found among the types of Myctophum nannochir, and the deserip- 
tion of the latter is partly drawn from specimens of each. Such being the case, the 
name nannochir becomes available in connection with the second of these forms, to 
‘which I shall here restrict it. The two species are extremely close, and immature or 
mutilated specimens are often distinguishable with difficulty. The species differ in 
‘the following respects: 
LEUCOPSARUM. 
Caudal peduncle deep, its least depth about half 
that of body. 
_ Head short, 33 to 33 in length. 
Maxillary shorter, the cheek wider, less taper- 
ing posteriorly. 
Luminous patches above and below tail occu- 
pying the whole length of caudal peduncle, in 
‘Tare cases somewhat shortened. 
Color lighter, the opercle usually with silvery 
luster, the iris with silvery pigment, and the fins 
lighter. 
Antro-anal spots usually 6. 
Ventral spots 4. 
NANNOCHIR. 
Caudal peduncle long and slender, its least 
depth two-fifths to one-third that of body. 
Head longer, 3} to 32 in length. 
Maxillary long, the preoperele very obliquely 
placed, thecheek long, tapering to an acute angle 
posteriorly. 
Luminous patches on tail short, usually oeccu- 
pying from one-fourth to one-third length of 
caudal peduncle, rarely longer than this. 
Color darker, the opercle black, the iris usually 
without silvery and the fins uniformly black. 
Antro-anal spots usually 7. Ventral spots 
usually 5. 
Specimens of N. leucopsarum were taken at stations 3227, 3307, 3308, 3325, 3329, 
8343, and 3348. 
The first five mentioned were in Bering Sea, north of Unalaska 
‘Island, at depths of 225 to 1,625 fathoms; the last two from off the coasts of 
‘Washington and California, depths 516 and 455 fathoms, 
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