538 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
The color, darker in general than in most species of the subgenus, 
is purplish brown, becoming darker below the first dorsal fin; bluish 
black on the belly, chin, and opercles; and brownish black about the 
occiput. The lower sides of the trunk and the median strip of the 
tail are silvery, as are also the sides of the head. The upper parts of 
the head and the snout are translucent: the front margin of the snout 
is black; the inner wall of the suborbital cavity is dark ventrally. 
The roof of the buccal cavity is mainly silvery; the branchial cavity 
is lined with white, for the most part, but with black posteriorly on 
its outer sides (leaving the extreme rim of the branchiostegal and 
opercular membranes white) ; the parietal peritoneum is blackish, but 
underlain by silvery. The first dorsal fin is dusky, the anal lighter; 
the paired fins are hght and clear, but with a black base which is pre- 
ceded ventrally by an area with metallic luster; the base of each ray 
in the second dorsal and anal fins is marked by a black spot. 
The striations are not so widely developed as in striatissimus, 
longiceps, longipes, and certain other species. The striated area ex- 
tends backward from the ventral base about half way to the anus, 
and forward, from above the ventral base, along the sides of the 
isthmus. The striations are obsolete on and just below the pectoral 
base, immediately anterior to the ventral bases, and on the gular 
membrane, which, however, is crossed by the usual black lines not 
similar to the true “ striae.” 
Table of measurements in hundredths of length to anus. 
| 
H. nascens. 
| 
H. lethonemus. 
| Type. Paratypes. 
Albatross station....... TR pe ere eae ae EAS 
‘Rotalilengthiin ime ee cee ee eee ee 
Mength tojanusjin mim) 42-2 2.5 ese a oe ee 
Lenethonhegd:..c.22. cee ee eee 
Onbittopreopercie n= senees ee eee see ne 
Length Ot Snoup.af6' -..)eenenepene ts. cones 
Length of upper jaw 
Depth of body 
Anus to ventral 
Ventral to gill-membrane...............-.---: 
Height of first dorsal base..............-. 
interdorsalispace:= >. se see eS 
Length of first pectoral ray 
Length of second pectoral ray 
Length of third pectoral ray....... 
Length of outer ventral ray....._.. 
Length of second ventral ray...... 
Softirays, firstdorsali se 2 oe 
Ventrali rays! S50 a ieeeen see arate 
Pectoralrays) isos csi ae weet rts 
Gill-rakers on lower limb of second arch... .... 18 i oa eee) Ss Se i: 19 1G eee 
1 A pseudocaudal developed. 
(nascens, being born, applied to this form to designate it as an in- 
cipient species. ) 
