98 
Fig. 9- Transverse section of a macro- and micro- 
cneme of Epizoanthus induratum. The dense incrusta- 
tion of the ectoderm and mesogloea has been largely 
omitted. Section taken from mid-column. Scale =S 
.10 mm. 
jective induratum (hardened) has been selected 
for the name of the species. 
With respect to bioluminescence, E. indura- 
tum is not so bright as Parazoanthus lucifcum. 
Whereas the source of luminescence in the latter 
species could not be determined, in the case of 
E. induratum it is very likely associated with 
the cells with large nonstaining granules that 
occur in the ectoderm around the mouth and in 
the entoderm of the actinopharynx and adjacent 
portions of the macrocnemes. There is no direct 
evidence that these cells are luminous; never- 
theless, their distribution in the polyp and the 
resemblance they bear to the luminous cells of 
Pelagia (Harvey, 1952, fig. 47) strongly sug- 
gest they have to do with the light production 
observed in the living zoanthid. 
Superficially the growth form of E. induratum- 
which occurs on Muricea very closely resembles 
Parazoanthus lucificum. However, unlike P. luci- 
ficum, E. induratum is not slimy and only in- 
frequently grows upon gorgonians. Among the 
species of Epizoanthus, E. induratum resembles 
only E. papillosum of the North Atlantic Ocean 
PACIFIC SCIENCE, Vol. XIV, April I960 
and then only in certain anatomical features. For 
example, the number of mesenteries is the same 
in both species; the sphincter muscle in E. in- 
duratum, although slightly weaker, is very much 
like that of E. papillosum, and in contraction 
the sphincter imparts a truncate appearance to 
the distal ends of the polyps of both species. 
Other features the two species have in common 
are few cells and lacunae in the mesogloea, heavy 
incrustation of sand, and prominent ridges on 
the scapulus. The two species differ chiefly in 
growth form and geographical distribution. Al- 
though it is conceivable that the same species 
might occur in both the North Atlantic and 
North Pacific oceans, the predominant habit 
of E. papillosum to form carcenoecia or occa- 
sionally small, unattached colonies strongly sug- 
gest we have to do with two species. In addition, 
the nonagreement in size and distribution of 
nematocysts, the inconspicuous microcnemes, its 
bioluminescence, and the peculiar aggregation 
of acidophilic gland cells around the mouth of 
E. induratum leaves little doubt that the species 
is new. 
Undoubtedly occasioned by the scanty ma- 
terial available to him, Carlgren, 1951, gives 
but a brief description of Epizoanthus gabrieli. 
On the basis of his description alone we could 
not fully compare E. leptoderma with E. gabrieli 
and for this reason felt justified in further dis- 
secting and sectioning a part of what remains of 
the holotype of E. gabrieli. Through this in- 
vestigation we have obtained a little more in- 
formation which we would like to offer here 
for incorporation with Carlgren’s description 
and thus more fully describe and illustrate his 
species. 
Epizoanthus gabrieli Carlgren 
Figs. 10, 11 
Epizoanthus gabrieli Carlgren, 1951, p. 438, 
pi. 14, fig. 6. 
MATERIAL EXAMINED: Holotype, U.S. Nat. 
Mus. Cat. No. 49463, one colony of five polyps. 
From Gabriel Bay, Espiritu Santo Island, Baja 
California. Collected by E. F. Ricketts, April 12, 
1940. 
Carlgren’s description of E. gabrieli has been 
found on re-examination to be accurate in 
the main. However, instead of "incrusted with 
