236 BULLETIN OF THE BUREAU OF FISHERIES. 



Diagnostic Synopsis of Families of Hexactinlb (adapted from McMurrich)." 



A. Tentacles in cyles — Actinina. 



a. Column simple. 



6. Tentacles cylindrical, smooth. 



_ , . , . , fMesenteries not numerous Halcampid^. 



c. Sphincter absent or weak< , , . 



'^ IMesentenes numerous AnTheid^. 



cc. Sphincter entodennal, tentacles deciduous BoLOCERiDiE. 



_ , . , ,/Acontia absent Paractid^. 



ccc. Sphincter mesodermal^ . ^. , . ^ 



I Acontia present Sagarthd^. 



„ ,. ^ , , , . .. J /Acrorhafri wartlike Bunodid^. 



cccc. Sphincter entodennal, circumscribedi .,..,. _ 



lAcrorhagi foliate Phyll.ictid^. 



,, „ ^ , _^ , /Simple Heteractid^. 



00. Tentacles warty or branchedi _ . „ 



ICompound Thaxassianthid^. 



666. Tentacles reduced to stomidia^ _ 



I. SlCYONID^. 



aa. Column in upper part with branched or globular processes DendromELId.E. 



B. Tentacles radially arranged — Stychodacylinidse. 



{Few, capitate Corallimorphid^. 

 Numerous, cylindrical Discosomid.B. 

 Nodulated Aureuanid.E. 



{Marginal cylindrical, disk tentacles wartlike, branched 

 or foliate Rhodactid.®. 

 Marginal pinnate, disk tentacles wartlike PhymanthidjS. 



aaa. Tentacles of various forms, not cylindrical CRJPTODENDRiDiS. 



METRIDIUM Oken, 1815. 



Metridium dianthus (Ellis), Oken. [Text fig. i.] 



Actinia dianthus Ellis, Phil. Trans., vol. 57, 1767. 



Metridium dianthus Oken, Lehrb. der Naturgesch., 1815. 



Actinia marginata Lesueur, Jour. Nat. Sci., Phil., vol. I, p. 172, 1817. 



Metridium wtart/irea/um Milne-Edwards, Hist. Nat. des Cor., vol. I, p. 254, 1857. 



Actinia marginata L. Agassiz, Cent. Nat. Hist. U. S., vol. in. i860. 



Actinoloba dianthus Gosse, Brit. Sea Anem., p. 12, i860. 



M etridium fimbriatum VerriU, Mem. Boston Soc. Nat. His., vol. I, 1864. 



marginatum Verrill. Inv. An. Vineyard Sound, p. 444, 1874. 



dianthus McMurrich, Ann. N. Y. Acad. Sci.. vol. xrv, 1901, p. 3. Torrey, Proc. Wash. Acad. Sci., vol. iv, 

 1903, 



(For full details of synonymy, see Andres, 1S83.) 



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. This pertains to almost every aspect 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 tlie European 

 coasts, b It may be doubted whether another of its relatives has a range of distribution at all comparable. 



oCf. Proceedings U. S. National Museum, vol. xvj, p. 134. 



bin identifying the local species with M. dianthus of Oken, I am but following several well-known authorities, especially 

 McMurrich, vide supra. 



