134 G Canadian Arctic Expedition, 1913-1918 



In confinement this species secreted from its column a coating of soft and 

 rather loose mucous. It is not attached to the tubes or burrows in which it 

 lives. It twists and wriggles about like an earth-worm when out of its bur- 

 rows. 



Type locality, Provincetown, Mass., in sand at low-water (U.S. Fish Com- 

 mission). 



It is possible that this species may prove to be the adult form of the peculiar 

 parasitic species frequently found adhering to the jelly fish, Mnemiopsis leidyi, 

 on the coast of New England in summer. The latter was named by me Edward- 

 sia leidyi in 1899 (Amer. Journ. Science, vol. VI, p. 496, figs. 2, 3). It has 

 not been raised much beyond the stage when it has eight short tentacles, and 

 sometimes rudiments of 8 others. It is smooth and lubricous, vary change- 

 al)Ie in form, from very long and slender to short ovoid or globular. Its colour 

 is reddish, rosy, or purplish 



Family CERIANTHID^. M. Edw. and Haime, 1852. 



Body much elongated, tapered to the base, without a basal disk, but usually 

 with a terminal pore. Tentacles of two kinds, marginal and labial; all elongated 

 and slender, very numerous in adults and arranged in manj^ cycles. One 

 siphonoglyjih. Mesenteries very numerous, unequal, arranged bilaterally, 

 tew (2 to 10 or more) reacli the posterior end. I\Iost species form coherent 

 tubes of mud, mucous, etc. Some live at the surface of the sea, even when large. 



Cerianthus Delle Chiage, 1830. 



Cerianthus borealis Verrill. 



Cerianthus borealis Veerill, Amer. Journ. Science, Vol. V, p. .5, 1873: Proc. 

 Amer. Assoc. Adv. Science, Vol. for 1873, p. 391, 1874 (in Explorations of 

 Casco Bay) ; Ann. Report U.S. Fish Comm. for 1883, p. 534, 1885; Webster's 

 International Dictionary, Edit, of 1904, pp. 1606, 1977 (good original 

 figures of type supplied by me ; also in an earher edition) . Smith and Harger, 

 Trans. Conn., Acad. Sci., Vol. Ill, p. 54, pi. II, fig. 5, 1874. Kingsley, 

 Tufts College Studies, No. 8, pp. 345-361, figs. 3-5, adult, and fig. 1, three 

 views of young Arachnactis, 19Q1. 



Cerianthus borealis McMuhrich, in Journ. Morphology, vol. V, p. 147, pi. IX, 

 figs. 9-13, 1891. E. L. Mark, Selections Embrvological IMonographs, 

 Polyps, pi. XII, figs. 16-23, 1884, in ]\Iem. Mus. Comp. Zool., vol. IX, 1884. 



Arachnactis brachiolata A. Agassiz, Proc. Boston, Soc. Nat. Hist., vol. IX, p. 

 159, 1862; Journ. Boston Soc. Nat. Hist. vol. VII, p. 525, 1863 (young).' 



Plate XXII; Figs. 1-4. Text Figures 19, 20, 21, a, b, b'; 22. 



This species grows to a very large size. Ordinary adult specimens may 

 have the body from 175 to 225 mm. in length and 40 to 50 mm. in greatest 

 diameter of body; breadth across expanded tentacles 125 to 150 mm. \5 to 6 

 inches); the longer inner marginal tentacles being 50 to 60 mm. long; outer 

 marginal ones 20-25 mm.; the oral tentacles 25 to 30 mm.; larger specimens 

 sometimes occur. One from off the coast of Maine was about IS inches long 

 (450 mm.) and 7 inches (175 mm.) across the expanded disk; others were some- 

 what larger. 



