236 
BULLETIN OF THE BUREAU OF FISHERIES. 
Diagnostic Synopsis of Families of Hexactini^ (adapted from McMurrich).® 
A. Tentacles in cyles — ^Actininse. 
a. Column simple. 
b. Tentacles cylindrical, smootli. 
^ , f Mesenteries not numerous Halcampid.®, 
c. Spnmcter absent or weakl , . 
^ IMesentenes numerous Antheid,®. 
cc. Sphincter entodermal, tentacles deciduous BotocERio^. 
o ^ j ,/Acontia absent ParacTid^E. 
ccc. Sphincter mesoderman . 
I Acontia present SAGARTno^E. 
o ^ j 1 • -t- j/Acrorhagi wartlike BuNOoiDiE. 
cccc. Sphincter entodermal, circumscribed^ ^ 
lAcrorhagi foliate Phyllactid,E. 
bb. Tentacles warty or branchedl^^™^^^ ' ' 
(.Compound Thalassianthid^. 
bbb. Tentacles reduced to stomidial Polyopid/E. 
I SlCYONID^. 
aa. Column in upper part with branched or globular processes Dendromelijd.®. 
B. Tentacles radially arranged — Stychodacylinidse. 
I Few, capitate Coralumorphid.!E. 
Numerous, cylindrical Discosomid.®. 
Nodulated Aurelianid® . 
( Marginal cylindrical, disk tentacles wartlike, branched 
or foliate RnoDACTro® . 
Marginal pinnate, disk tentacles wartlike Phymanthid®. 
aaa. Tentacles of various forms, not eylindrical CeipTodendrid®. 
METRIDIUM Oken, 1815, 
Metridium dianthus (Ellis), Oken. [Text fig. i.] 
Actinia dianthus ElUs» Phil. Trans., vol. 57, 1767. 
Metridium dianthus Oken, Tehrb. der Naturgesch., 1815. 
Actinia marginata Tesueur, Jour. Nat. Sci., Phil., vol. i, p. 172, 1817. 
Metridium margmatum’M.ilne-^dwa.rds, Hist. Nat. desCor., vol. i, p. 254. 1857. 
Actinia marginata T. Agassiz, Cent. Nat. Hist. U. S., vol. ni, i860. 
Actinoloba dianthus Gosse, Brit. Sea Anem., p. 12, i860, 
Metridium fimbriaium Verrill, Mem. Boston Soc. Nat. His., vol. i, 1864. 
marginatzim Verrill, Inv. An. Vineyard Sound, p. 444, 1874. 
dj'awiAwj' McMurrich, Ann. N. Y. Acad, Sci., vol. xiv, 1901, p. 3. Torrey, Proc. Wash. Acad. Sci., vol. iv, 
1902. 
(For full details of synonymy, see Andres, 1883.) 
This beautiful actinian, often designated as the “fringed sea anemone,” is altogether the most 
common and at the same time the most conspicuous of our actinian fauna. It abounds almost every- 
where from New York to Nova Scotia, from tide pools to a depth of 75 fathoms and beyond, and is one 
of the largest anemones of the region. 
It is a remarkably variable species. Tliis pertains to almost every aspeet of the creature — size, 
color, habitat, structure, mode of propagation, etc. In distribution it seems to be almost cosmopolitan, 
being found upon both the eastern and western coasts of America, and variously over the European 
coasts, b It may be doubted whether another of its relatives has a range of distribution at all comparable. 
«Cf. Proceedings U. S. National Museum, vol. xvi, p. 134. 
*>In identifying the local species with M. dianthus of Oken, I am but following several well-known authorities, especially 
McMurrich, vide supra. 
