Zoantharia — C utress and Pequegnat 
there is a difference in the zoogeographical dis- 
tribution, host, and polyp size between the two 
species, probably the most important diagnostic 
character is the absence of holotrichous nemato- 
cysts in P. lucificum while they are relatively 
abundant in P. tunicans . 
In summary, the distinguishing features of 
P. lucificum are its brilliant bioluminescence, 
sliminess, affinity for the gorgonian Muricea 
calif ornica, lack of holotrichs, and, in most cases, 
its complement of mesenteries. 
Family EPIZOANTHIDAE 
Epizoanthus Gray, 1867 
Epizoanthus Gray, 1867, p. 237. Type species 
by monotypy: Duseideia? papillosa Johnston, 
1842, pp. 190, 251 (in part), text fig. 18 (not 
pi. 16, figs. 6, 7), = Epizoanthus incrustatus 
(Diiben and Koren, 1847), p. 268. Gender: 
neuter. 
DIAGNOSIS: Epizoanthidae with a single mar- 
ginal sphincter muscle in the mesogloea. Scapus 
and coenenchyme incrusted with foreign ma- 
terial. Ectoderm usually continuous but may oc- 
casionally be discontinuous. Mesogloea often 
with cell islets and lacunae. Polyps either co- 
lonial or solitary. Coenenchyme bandlike, in- 
crusting or greatly reduced in solitary forms. 
Dioecious. 
Epizoanthus leptoderma n. sp. 
Figs. 4-6 
TYPE MATERIAL: Holotype, U.S. Nat. Mus. 
Cat. No. 50974, two portions of one colony 
with a total of 80 to 90 polyps. From a shale 
reef, depth 40 feet, Corona del Mar, California. 
Collected by Robert Given, August 25, 1957. 
DIAGNOSIS: Colony large, consisting of nu- 
merous, moderately crowded, elongate polyps 
arising from a moderately thick, incrusting cce- 
nenchyme. Scapus thin-walled. Ectoderm of the 
scapus and coenenchyme moderately incrusted 
with sand. Ridges of the scapulus indistinct, to 
18 in number, agreeing with the macrocnemes. 
Marginal sphincter muscle in the mesogloea, 
moderately strong, broad and transversely strati- 
fied. Tentacles and mesenteries to 36 in number. 
Mesogloea with few lacunae and cell islets but 
93 
with single elliptical cells especially in the re- 
gions of the oral disc and actinopharynx. 
DESCRIPTION: Size. In the preserved semi- 
contracted state the polyps vary in length and 
diameter from 5 by 1.5 mm. to 20 by 5 mm. The 
largest portion of the colony is about 4 cm. in 
diameter at the base. 
External Aspects. Polyps elongate, moderately 
crowded and arising from a moderately thick, 
incrusting coenenchyme. Scapus thin-walled, 
allowing the mesenterial insertions to show 
through. Surface of the scapus and coenenchyme 
with a moderately dense incrustation of fine 
black and white sand. Ridges of the scapulus to 
18 in number, indistinct in contracted speci- 
mens. Tentacles of medium length, thin, num- 
bering to 36 in large polyps. Color in life tan, 
with narrow, transverse, brown bands on the 
tentacles. Color in alcohol, scapus and coenen- 
chyme gray, tentacles gray with one to several 
narrow, transverse, violet bands. The species oc- 
curs on shale reefs at depths of 15 to 45 feet. It 
is common on protected ledges. 
Marginal Sphincter Muscle. In the mesogloea, 
moderately strong, broad and transversely strati- 
fied (Fig. 5). 
Mesenteries. Usually agreeing in number with 
the tentacles. Those of the 10 largest specimens 
were (36) 1, (34) 1, (33) 4, (32) 2, and 
(30) 2. Several of the smallest specimens had 
30 mesenteries. Polyps with 36 mesenteries have 
18 macro- and microcnemes. Mesogloea lamina 
of the mesenteries thin. Retractor muscles of 
the macrocnemes very weak and diffuse (Fig. 
6 ) . The microcnemes scarcely extend above the 
column entoderm. Gonads were not apparent- 
in the specimens examined. 
Actinopharynx. Ectoderm with few gland 
cells and with olive-colored pigment granules 
in the basal portion. Siphonoglyph distinct, 
slightly longer than the indistinct hyposulcus. 
Mesogloea. With a few small lacunae and a 
few cell islets but with rather numerous, single, 
elliptical cells especially in the regions of the 
oral disc and actinopharynx. The elliptical cells 
of the column are more numerous next to the 
entoderm. Mesogloea of the column about four 
or five times the thickness of the ectoderm, con- 
taining a little sand and an occasional sponge 
spicule. 
