PHILIPPINE MACROUROID FISHES—GILBERT AND HUBBS. 523 
across the isthmus. The short spiny gill-rakers are fewer than in any 
form previously described with the exception of tenuis, there being 
but 12 or 13 on the outer two arches; the first gill-arch is bound down 
by membrane above its angle and near its anterior end. Seven 
branchiostegals. 
The anus is located immediately before the origin of the anal fin, 
its distance from the base of the outer ventral ray being equal to the 
distance from tip of snout to hind margin of orbit, and a little longer 
than the distance between the ventral base and the isthmus at the 
fold of the gill-membranes. 
The two ventral lens-shaped bodies are present in the usual posi- 
tions; both are circular in outline; the diameter of the anterior one, 
located in advance of the ventrals, is about two-thirds that of the 
posterior one, which is situated immediately before the anus. The 
Fic. 31.—HYMENOCEPHALUS GRACILIS. TYPE. 
two organs, as usual, are connected by a black-surfaced strand of 
tissue along the inner surface of the abdominal body wall. 
The scales are almost entirely lost, but three are present near the 
origin of the lateral line; two are overlapped by the last of the scale- 
like bones flooring the sensory canal in advance of the lateral line. 
The scales are round and marked with concentric striae, but are 
wholly spineless. One, bearing a lateral line pore, is separated pont 
the origin of the first dorsal by 24 rows of scales. 
This species‘is sharply distinguished from all others of the genus 
previously described, with the exception of 1. tenwis, by the presence 
of weak denticulations on the distal portion of the dorsal spine; the 
spine is broken, but 5 denticulations remain on a distal portion only 
half as long as the orbit; the proximal smooth portion of the spine 
is two-thirds the postorbital length. The length of the first dorsal 
base is about half the interval between the dorsals, or two-thirds 
the postorbital. The rays of the paired fins are exceedingly slender 
and weak; the pectoral fin is just equal in length to the postorbital 
