GILBERT: FISHES OF THE SUBGENUS LUXILUS


ated parallel and dorsad to the main lateral stripe; a jet-black predorsal
streak; few apical radii on scales; four or five prominent scallops on
posterior margin of those scales situated in or close to the lateral line;
weakly developed nuptial tubercles on top of head and back, present
in one row along lower jaw and absent from tip of chin; body slender
and terete at all sizes.
 Distinguished from N. pilsbryi by the following pigmentary char-
acters (see figure 5A and table 2): Lateral stripe on posterior part of
opercle curved sharply upward, not bordering upper half of posterior
margin; lateral dark stripe extending little or not at all below lateral
line posterior to head and anterior to caudal peduncle, and absent
from a small area above middle part of lateral line; black pigment
present over all of cleithral area dorsad to pectoral insertion, becoming
jet-black in breeding individuals; pigment in lateral stripe on caudal
peduncle unequally distributed around lateral line, more present
above than below; pigment more dense around edges of dorso-lateral
scale pockets, forming crooked parallel lines along side of back, the
stripes converging posteriorly with those from opposite side of body;
red and black pigment usually more pronounced, particularly in
breeding males.
 DESCRIPTION. Counts and measurements are given in tables 5
and 9 through 15. All distinctive pigmentary characters of the spe-
cies are analyzed in table 2 and are shown in figure 5A. Characters
mentioned in the above diagnosis are not repeated in the following
paragraph:
 Anterior dorso-lateral scales 14.to 16 (18); circumferential scales
(25) 26 to 28 (29); sum of anterior dorso-lateral and circumferential
scales (39) 40 to 44 (46); an olive area about 21/ times as wide as mid-
dorsal stripe (not so sharply defined as in N. cornutus) extending along
body on either side of mid-dorsal stripe; side of body silvery with an
intense black stripe running from snout to end of caudal peduncle,
this stripe often overlain with a plumbeous coloration which disap-
pears in preservative; mid-dorsal stripe black, slightly more than half
as wide as eye, and extending around base of dorsal fin; breast, belly,
and lower side of head silvery, becoming flame-red in breeding males;
back olivaceous; lips, preopercular bar, and pectoral axil bright blood-
red in breeding males; top of head dark gray to black, especially dark
in breeding individuals; branchiostegals ordinarily colorless, becom-
ing deep red in breeding males; fins ordinarily pale, becoming orange-
red in breeding males except for gray borders; red most pronounced
in dorsal fin, with some green beneath; red often more reduced in
area and/or intensity in other fins, and in low breeding males largely


1964