338 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
be formed mainly as thickenings of the mesoglcea, but the larger are hollow, their cavity communicating 
with the ccelenteron. Inturnings of the ectoderm may also occur, forming the ectodermal bays. 
The sphincter is single, mesoglceal, and strong, extending nearly across the mesogloea. Proxi- 
mally the mesogkeal cavities are small and circular; distally they are oval and elongated. 
The tentacles possess a peripheral zone of narrow nematocysts, among which are many gland 
cells. The mesogloea is thin, but on its ectodermal border presents long, delicate, branching plaits for 
the support of the longitudinal muscle. The endoderm is narrow and contains zooxanthelke of two 
kinds, large and small. The disk closely resembles the tentacles in structure, and also exhibits the 
peculiar ectodermal musculature. 
The stomodseum may be strongly oval or nearly circular in outline, and the ectoderm is thrown 
into eight or nine folds on each side, corresponding with the mesenteries (figs. 23). The tube is 
but slightly truncated opposite the gonidial groove, the sulcar directive mesenteries extending from 
each corner. 
The mesenteries are brachytypic; about ten pairs usually occur on each side. The perfect 
members are very narrow and arranged at equal distances apart all round the stomodseal wall. The 
mesenterial mesogloea and endoderm are very thin, the latter crowded with zooxanthelke and small oval 
nematocysts. The parieto-basilar and retractor muscles are clearly recognizable. Toward the insertion 
of the mesentery in the column-wall the mesogloea is swollen and thrown into small, irregular plaits 
for additional support to the musculature. A basal canal and numerous other vertical canals and cell- 
inclosures occupy nearly the whole length of the mesentery. The reflected ectoderm is but feebly 
developed, and the mesenterial filaments are of the usual Zoanthean type. Toward the base of the 
polyp the mesenteries unite with one another and form a reticular structure, filling the whole of the 
coelenteron. 
No gonads have been met with in numerous specimens sectionized. 
Localities . — Guadeloupe and St. Thomas (Duchassaing & Michelotti), Bahamas (McMurrich), 
Jamaica (Duerden), Porto Rico (U. S. Fish Commission). 
Genus PROTOPALYTHOA Verrill. 
Gernmaria, Duchassaing et Michelotti, 1860, p. 55; McMurrich, 1889, p. 131, etc.; Haddon,T898, p. 639, etc.; Duerden, 1898, 
p. 350; Carlgren, 1900, p. 106. 
Protopalythoa, Verrill, 1900, p. 562. 
Brachycnemie Zoanthex, with a single mesoglceal sphincter muscle. Solitary or connected by 
ccenosarc. The body-wall is incrusted. The ectoderm discontinuous or continuous. Lacuna: and 
cell-islets are found in the mesogloea. Polyps dioecious or monoecious. 
We owe to Professor Verrill (1900, p. 502) the recognition that Duchassaing A Michelotti’s familiar 
name Gernmaria was preoccupied by McCready in 1859 in the Hydrozoa, and also to Verrill the sub- 
stitution for Gernmaria of the term Protopalythoa. In doing this he has assigned as the type of the 
genus Gernmaria variabilis, a species described by me in 1898, and again referred to below. None of 
Duchassaing & Michelotti’s species was regarded as sufficiently well known or recognizable to occupy 
this position. 
Verrill (p. 563) comments upon the close relationship between the genera Palythoa and Proto- 
palythoa, but wisely decides to keep them apart, a course which, for the time being, will tend to facili- 
tate the study of their different representatives. 
Under the name Gernmaria the genus has been defined in practically the same terms by all recent 
students of the Zoanthex. 
Protopalythoa variabilis (Duerden). Pis. II, VII, Figs. 6, 27. 
Gernmaria variabilis, Duerden, 1898, p. 350, pi. xvna, fig. 5; pi. x villa, iigs. 7-9; von Heider, 1899, p. 130, pi. xvn, figs. 22-29. 
Protopalythoa variabilis, Verrill, 1900, p. 562. 
This species was first described from specimens obtained from Port Henderson, Jamaica, and 
von lleider (1899) has since provisionally identified as the same a form from the distant locality of 
Singapore. In the Fish Hawk collections from Ilucares are fourteen specimens which are undoubtedly 
this species, and agree with the Jamaican representatives in the character suggested by the specific 
