FISHES OF HAWAIIAN ISLANDS. 
595 
In some specimens examined, a row of 5 to 7 luminous spots occupies the median line on the lower 
side of the caudal peduncle, one under each scale. Others have a row of similar but stronger spots 
on the back of the caudal peduncle. In either series the spots vary from 5 to 7 in number. Similar 
arrangements are found in Rhinoscopelus coccoi and andrex (Liitken, Spolia Atlantica, Scopelini, pp. 243 
and 245). From the fact that no individual possesses both the dorsal and the ventral series, Liitken 
suggests that the position of these spots may be a sexual character. Dissection of three specimens of 
each kind of C. chcerocephalus has shown that such is the case, the males having the dorsal series of 
stronger spots. The smallest specimen showing a trace of these spots is 25 mm. long, and the longest 
specimen in which none are apparent is 28 mm. Males are somewhat more abundant than females. 
General color dark on back, silvery on lower half of sides, with bluish and reddish reflections ; 
dorsal and caudal dusky, base of caudal blackish. 
Specimens were taken at the following stations : No. 3912, south of Oahu, surface ; 3926, west of 
Oahu, surface; 3927, west of Niihau, surface; 3929, south of French Frigate Shoals, surface; 3930 near 
Laysan Island, surface; 3932, near Laysan Island, surface; 3980, south of Oahu, surface; 4009, east of 
Kauai, surface; 4011, west of Oahu, surface; 4145, west of Niihau, surface; 4188, between Honolulu and 
San Francisco, lat. N. 28° 13 r 42 // , long. W. 145° 44', surface. 
Centrobranchus chcerocephalus Fowler, Proc. Ac. Nat. Sci. Phila., 1903 (Jan. 13, 1904), 754, near the Sandwich [Hawaiian] 
Islands. (Type, No. 7972, A. N.S. P., Coll. i>r. Wm. H. Jones.) 
Centrobranchus gracilicaudus, new species. Plate 69, Fig. 2. 
Type 33 mm. long, from the surface at station 4145, west of Niihau Island; type, No. 51518, U. S. 
Nat. Mus. 
Closely related to C. chcerocephalus, with which it agrees in all essential features except the following: 
(1) Supra-anals arranged in an oblique line, the middle spot vertically above the vent, the lowest ver- 
tically above the fourth of the ventral series. The species differs from (1 chcerocephalus, therefore, 
very much as Rhinoscopelus andrex (Liitken) differs from Rhinoscopelus coccoi (Cocco). (2) Anals 
averaging a little more numerous, in the 11 specimens collected, the sum of the two groups being 16 in 
8 cases, 17 in 12 cases, 18 in 2 cases. The anterior group consists always of 6 or 7 spots (6 in 15 cases, 
7 in 7 cases), while in chcerocephalus 5 and 6 are equally abundant and 7 is rare. Of postero-anals, 
there are 9 in 3 cases, 10 in 7 cases, 11 in 12 cases. In chcerocephalus 10 is much more abundantly 
represented than 11. The limited number of specimens in the species here described renders the 
averages not wholly reliable, but they are obviously different from the averages in chcerocephalus. 
(3) Scales of mid-lateral series more persistent, and deeper in proportion to their width. (4) Body 
deeper and snout somewhat less projecting. 
Dorsal 12; anal 19; scales in mid-lateral series 38 or 39. Greatest depth of body 23 hundredths of 
the total length without caudal; least depth of caudal peduncle 5; length of head 28; diameter of orbit 
7; interorbital width 7.5; length of snout 7; projection of snout beyond maxillaries 4; length of max- 
illary 17 ; distance from tip of snout to front of dorsal 47, from front of dorsal to adipose dorsal 29, from 
front of adipose dorsal to rudimentary caudal rays 26, from tip of snout to origin of anal 56; length of 
pectoral 14; length of ventral 10. 
With the exceptions noted, the shape of the body, size and relative position of fins, character of 
scales, and the number and arrangement of the photophores are as in C. chcerocephalus. 
Specimens were taken at the following stations: No. 3926, west of Oahu, surface; No. 3927, west 
of Niihau, surface; No. 3929, southwest of French Frigate Shoals, surface; No. 3930, near Laysan 
Island, surface; No. 4011, west of Oahu, surface; No. 4145, west of Niihau, surface. 
KEY TO HAWAIIAN SPECIES OF MYCTOPHTJM. 
a. Three pairs of ventral photophores along the median line .Jibulatum,, p. 596 
ao. Four pairs of ventral photophores along median line. 
b. Posterolateral single. 
o. Supra-anals forming a straight line rising obliquely from near the last ventral margaritatum, p. 596 
cc. Supra-anals forming an obtuse-angled triangle, the middle and lower photophores at about the same level, 
the lower much in advance evermanni, p. 597 
d. Supra-anals forming an obtuse-angled triangle braueri, p. 598 
