EASTERN COAST OF THE UNITED STATES. 45 



10. Basal disk wanting, polyp swimming freely (Arachnactis) 33 



10. Basal disk wanting, polyp sedentary (11) 

 10. Basal disk distinct (14) 



11. Tentacles numerous, of two kinds ( Cerianthus) .... 32 



11. Tentacles numerous, marginal only (12) 

 11. Tentacles twelve, of one kind (13) 



12. Column of uniform texture (llyanthus) 26 



12. Column with a thickened epidermis in the middle (Edwardsia) 27 



13. Mouth with prominent lobes (Bicidium) 31 



13. Mouth simple, column with suckers (Halcampa) 29 



14. Disk frilled, tentacles very numerous, fringe-like at the margin (Metridium) 21 



14. Disk plain, tentacles slender, not contractile (Dysactis) 26 



14. Disk plain, tentacles contractile (15) 



15. Walls covered by crowded verruca? (Bunodes) 1 o 



15. Walls with distant verruca? ; tentacles large {Rhodactinia) 18 



15. Walls verrucose above ; margin with trilobed verrucas (Aulactinia) 20 



15. Walls smooth or with inconspicuous suckers (16) 



16. Column smooth, with a thickened fold above, tentacles few (Metridium, young) 21 



1 6. Column with suckers, but no fold, tentacles numerous ( Cereus) 24 



1 6. Column smooth throughout, tentacles few {Rhodactinia, young) IS 



Explanation of Plate I. 



(Figures 10, 11, from nature, by Wm. Stimpson; 8, 9, 14, 15, by the author; the others by E. S. Morse.) 



Fi<*s. 1-8, Bunodes Stella : 1-3, young when first excluded ; 4, adult polyp when contracted ; 5-7, different views 

 of the expanded polyp; 8, magnified view of the mouth, a a the two primary radii, corresponding with the antero- 

 posterior axis, b b and c c the other radii of the same cycle. 



Fif. 9, Rhodactinia Daoisii, mouth somewhat enlarged ; the letters correspond to the same parts as in fig. 8. 



Figs. 10, 11, Halcampa producta : 10, polyp when taken from the sand and allowed to expand ; 11, form when 

 expanded in its burrow. 



Figs. 12, 13, Edwardsia sipunculoides : 12, polyp of the natural size drawn from a specimen somewhat con- 

 tracted in alcohol; 13, disk and tentacles considerably enlarged. 



Fi<»s. 14, 15, Bicidium parasiticum : 14, polyp natural size; 15, enlarged view of the disk and mouth. 



Addenda. 



Since this paper went to press, I have been able to examine the " Memoire sur les Coralliaires des Antilles," by 

 Duchassaing and Michelotti, Turin, 1860, a work not previously accessible to me. These authors have described a 

 species under the name of Muricea elegans (p. 19), which is apparently identical witli Muricea laxa Verrill, recently 

 described in the Bulletin of the Museum of Comparative Zoology. For the species called by the same name in 

 the present paper I would, therefore, propose the name Muricea pendula. In the same work (p. 50) the name 

 Zoanthns parasiticus has been preoccupied. The species herein described under that name I propo-e to call 

 Zoanthus americanus. 



memoiks host. soc. nat. hist. Vol. I. 12 I' ublished July, 1864. 



