Actinaria G 91 



It may have either one, two, three or more siphonoglyphs and directive 

 pairs of mesenteries according to the positions whence fragments are taken 

 or a basal bud arises. It rarely buds from the stomodeal region. Longi- 

 tudinal fission is not infrequent. 



The mesenteries also show considerable variations in their arrangements 

 largely, no doubt, in consequence of these asexual reproductions. 1 



Its distribution is circumpolar. It is essentially a shallow water species, 

 seldom found in more than 25 fathoms. It frequently occurs above low-water 

 mark amongst stones, on piles of wharves, and especially in cavernous places 

 in shore cliffs. It likes the shade. 



On the Eastern American coast it extends southward to Long Island sound 

 and northern New Jersey. It is much more abundant north of Cape Cod, on 

 the coasts of Massachusetts and Maine and in the Bay of Fundy, etc., where 

 it becomes very large; also in the Gulf of St. Lawrence, etc. 



On the northern European coasts it is abundant and extends southwards 

 to England, etc., and varies in colours much as it does on the American coast. 

 It sometimes becomes large there. 



The Canadian Arctic Expedition specimens were from Port Clarence bay, 

 Alaska, Station 20y, in 2 to 3 fathoms, mud and thread algae, August 4-13. 

 Two medium-sized specimens, collected oy F. Johansen; several young ones 

 were on a sponge, from the same place. 



Its range extends southward on the Pacific coast to San Francisco, where 

 it was found by Dr. Wm. Stimpson and described by me as a new species (M. 

 fimbriatum) many years ago (1865). His specimens were very large, pale orange 

 or salmon-colour, dotted with brown; lips orange. 



On the North Palcifio coast it has been reborded from only a few places 

 between Bering strait and San Francisco. It was recorded by me, in 1869, 

 from Puget sound. Prof. Coe, as nientioned above, gives Victoria as a locality. 

 McMurrich described it from Puget sound, and recorded it from Sitka (observed 

 by Calkins). 



Possibly it has been carried to San Francisco from more northern localities 

 on the bottoms of vessels. It is well adapte<d for such transportation, like 

 Sagartia lucice, which has now been found on the English coast, at Naples, and 

 at San Francisco, although only known from southern New England a few 

 years ago. Being a very hardy shallow water species and very prolific it ma} 

 well be carried across the oceans on vessel bottoms. 



Metridiwn dianthus is also very hardy, as indicated by its northern and 

 arctic distribution. Like S. lucice, it can withstand freezing. I have kept 

 specimens in dishes of water until frozen within a solid mass of ice. When 

 slowly thawed out they completely revived. 



When deprived of food for a long time a large one will gradually decrease 

 in size and numbers of tentacles. Some that I have tried became less than half 

 their original sizes and looked like young ones. 



After an experience of over fifty years, I have not been able to find any 

 reliable differences between the North Pacific and Atlantic forms. McMurrich 

 also failed to find any tangible anatomical differences (1921). At present 

 there seems to be no doubt of the identity of the American and European 

 forms, though Andres kept them distinct. 



Prof. McMurrich has endeavoured to restore for this species a name (senilis) 

 used by Linnaeus, for a small indeterminable species very imperfectly described in 

 1761. (Fauna Suecica). The description does not in the least apply to this 



! For descriptions and discussions of the numerous variations of the mesenteries ard siphonoglyphs 

 of Metridium, and also its sexual modes of reproduction, see G. H. Parker: The mesenteries and siphono- 

 glyphs in Metridium marginatum, in Bull. Mus. Comp. Zool., Vol. XXX, No. 5, pp. 259-273. with plate; 

 also in the same work, Vol. XXV, pp. 43-53, 1899. H. B. Torrey, Observations on Monogenesis m Met- 

 ridium, in Proc. Calif. Acad. Science, ser. 3, vol. i, No. 10, pp. 345-360, pi. XXI, 1898; also in Proc. Wash- 

 ington Acad. Sci., Vol. IV, pp. 395-406, 1902. C. W. Hahn, Dimorphism and Regeneration in Metridium, 

 in Journ. Exper. Zool., Vol. ii, No. 2, pp. 225-235, 1905. 



