592 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
a line parallel with base of anal fin, the seventh elevated; on a line joining sixth with posterolateral; 
6 posterior anals. The distinguishing features are especially the elevated second ventral, the presence 
of but 2 (instead of 3) supra-anals, and the very high position of the uppermost series. 
The differentiation of the upper half of each photophore and its superficial separation from the lower 
half by a pigment band can be made out only when the photophores are uninjured and are still pro- 
tected by the scales. It is possible that all species heretofore grouped in Collettia and JEthoprora pos- 
sess the character of divided photophore. In this case we should range them under the oldest name, 
Diaphus, as we do not consider the presence or the extent of the preocular photophore of generic 
importance. If the current system of minute subdivision be followed to its logical extreme, D. 
urolampus must be considered the type of a new genus, distinguished by the absence of preocular 
photophores, and D. chrysorhynchus the type of another characterized by the large preocular photo- 
phore, which covers the entire snout (as in JEthoprora) . 
Diaphus urolampus Gilbert <fc Cramer, Prac. U. S. Nat. Mus., xix, 1897, p. 408, pi. 38, fig. 1. 
Diaphus chrysorhynchus Gilbert & Cramer. 
Four specimens were taken at the following stations: No. 3834, off Kaunakakai, Molokai, surface; 
3921, off Honolulu, surface; 4117, off northwest coast Oahu, 253 to 282 fathoms. 
The specimen from station 4117 came to hand in perfect condition and must have entered the 
trawl near the surface. All other specimens known, including type and cotypes, were obtained in 
the surface tow net. 
The bluntly rounded snout, covered by the preocular photophore, gives a strong resemblance to the 
species of JEthoprora, which differ only in their simple photophores. It is not improbable that 
perfect specimens of JEthoprora and Collettia, with scales still in place, will show their photophores 
also to be divided by a black pigment line, in which case the species may be united under the oldest 
name, Diaphus. Nyctophus, Cocco, used by Brauer for this group, was proposed solely as an amended 
form of Myctophum, and is therefore not available. 
The photophores of D. chrysorhynchus show the following characteristic arrangement: Two lower 
pectorals on each side forming diverging lines extending from first thoracics to middle of pectoral base, 
third pectorals high on sides, nearer lateral line than pectoral fins; fourth thoracics elevated, on a level 
with ventral base, vertically over the third thoracics; five ventrals,. the first, second, and third pairs 
forming oblique diverging lines, the third a little above level of ventral base; supra-anals 3, forming a 
nearly vertical line from vent, the uppermost more widely spaced, and in contact with the lateral line; 
the first anal (interpreted as supra-anal in description cited below) elevated, in a line joining second 
anal and upper supra-anal; second to fifth anals in a straight or gently curved line, the sixth strongly 
diverging, in a line which includes the posterolateral; the posterolateral in contact with the lateral line; 
five anals in the posterior series. 
In the arrangement of its photophores this species agrees very closely with D. theta Eigenmann & 
Eigenmann and D. adenomus, but theta has the upper lateral spots much less elevated and the first 
anal on a level with the others, while adenomus has the upper pectoral much less elevated, and those 
of the anterior anal group describe a wide curve. D. chrysorhynchus shows no variation in the number 
or arrangement of its photophores (except that in one specimen there are on one side 6 instead of 5 
posterior anals) nor in the size of its preocular luminous area. 
Diaphus chrysorhynchus Gilbert & Cramer, Proc. U. S. Nat. Mus., xix, 1897, 409, pi. 38, fig. 3 (not fig. 2, as erroneously 
indicated on the plate and in the description). 
Diaphus adenomus, new species. Plate 68. 
Type, a female with developed spawn, 16 cm. long, from Albatross station 4106, the Kaiwi Channel 
between Oahu and Molokai, depth 335 to 350 fathoms; type, No. 51588, U.S.Nat.Mus. 
Head 28 hundredths of total length, excluding caudal; greatest depth of body 23; least depth of 
caudal peduncle 10; distance from last anal ray to first caudal ray 18; length of pectoral 10; length of 
inner ventral rays 17; base of anal 19; base of dorsal 21; diameter of eye 6; width of middle of inter- 
orbital space 8.5; length of snout 4.5; length of maxillary 20.5. D. 15; A. 15; P. 12; V. 9; scales in 
lateral line 36. 
