74 
PACIFIC SCIENCE, Vol. VIII, January, 1954 
surance what names should be applied to the 
Diplacanthopoma specimens at hand. 
It would be an easy matter (and one for 
which the precedent has already been set in 
Diplacanthopoma) to describe the Hawaiian 
species as new. However, I can see no ad- 
vantage in doing so at present. It would ap- 
pear preferable to describe the Hawaiian spec- 
imens sufficiently for specific recognition, 
leaving the names to be applied to them to 
the time when the genus can be revised on a 
world-wide basis. 
The two specimens in the present collec- 
tions appear to represent two species. It is 
true that most of the differences between 
them could be attributed to discrepancies in 
preservation, to size, to the regeneration of 
the tail in one, or to individual variation. 
There are, however, a few characters that ap- 
parently could not be attributed to any of the 
above categories. 
Diplacanthopoma (Privers-andersoni 
Alcock) 
Tables 1, 2; Figs, l/, 2a, 3^ 
I Diplacanthopoma Rivers- Andersoni Alcock, 
1895: 144 (Arabian Sea); Alcock, 1895.^, 
pi. 17, fig. 1 (from the holotype); Alcock, 
1899: 98-100 (on the holotype); Norman, 
1939: 91 (species listed). 
MATERIAL EXAMINED: 1 male, 292 mm. in 
standard length, taken off the Mauna Loa 
lava flow, Hawaii, by Gosline, Hayes, Keen, 
and Ellis, June 6, 1950. 
Body tapering to a rather fine point poste- 
riorly, the 10 caudal rays articulating with a 
single, undivided hypural and forming a very 
narrow, pointed tail. Head large, subcylin- 
drical, entirely scaleless. Maxillary reaching 
about to level of posterior border of eye. 
Posterior nostril a large hole just ahead of 
eye, partially covered over in front by a flap 
of skin. Anterior nostril in a short tube at 
rim of snout. Large sinuses on head: one un- 
der each ramus of lower jaw, a second below 
preopercle, a third within the fleshy flap above 
the opercle, all these sinuses inflated in this 
specimen. Snout rim, from beside premaxil- 
lary pedicels to about opposite middle of eye, 
with an elongate, slit-like cavity, closed over 
at two points by narrow, fleshy bridges. Free 
preopercular border somewhat angular below, 
but without developed spines. Lower points 
of opercle not penetrating flesh. 
Teeth all small but not of equal size, some 
Fig. 2. a, Diplacanthopoma {rivers-andersoni1)\ b, Di- 
placanthopoma (sp.?); c, Cataetyx hawaiiensis; d, Volcanus 
lineatus; e, Pycnocraspedum armatum. Scaled portions of 
head are indicated by stippling. The limit of the scaly 
lobe on the pectoral fin base is shown by the dotted 
line. The limits of the fleshy sheaths along the bases 
of the dorsal and anal in Diplacanthopoma are shown 
by broken lines. The lateral lines of the body are shown 
in three ways: the superior, rudimentary line of Cataetyx 
by dots; developed lateral lines consisting of papillae 
penetrating the scales by dashes; and continuous, 
fleshy tubes running along the surface of the body by 
solid lines. 
