EASTERN COAST OF THE UNITED STATES. 3 



central cavity or central axis, and the polyps adhere to foreign bodies directly by their 

 bases or by the ccenenchyma. 



II. Gorgonid^e ; in this group the polyps are short, cylindrical ; connected laterally by a 

 porous ccenenchyma, at their bases by a common membrane, and by specialized lono-i- 

 tudinal canals ; and arranged around a firm central axis which is secreted from the 

 common basal membrane. The communities are attached to foreign bodies by the ex- 

 ])anded base of the central axis. 



III. Pennatulid^e ; this division includes those that are united into communities which 

 are unattached and capable of voluntary locomotion. The polyps are regularly arranged 

 at the upper part of the structure, which contains special ducts and a central cavity, some- 

 times subdivided or inclosing a solid axis attached to the walls by muscular fibres. The 

 lower extremity is bulbular and capable of exjiansion and contraction by means of a well- 

 developed common muscular system. 



The nature and rank of these three groups have been variously estimated by naturalists. 

 Milne -Edwards, who is among the highest authorities, in his latest works treats them 

 as families. But since they are characterized by modifications of the most important 

 structures beneath those characteristic of the order, and at the same time include other 

 inferior groups that have the nature of families, I am led to consider them as sub-orders. 



Sub-order I. A l c y n i d m. 



The characters of this division have been sufficiently indicated above for our present 

 purpose. It embraces several well-marked families; viz: Alcyonince Ehr. (restricted), Xenince 

 Ehr., Cornularince Ehr. (emended), TvMporidce Fleming. Of these, Alcyonince and Cornalarince 

 are alone represented on our coast, so far as at present known. 



Family Alcyonince Ehrenberg. 

 Alcyonidce (pars) Dana, Zoophytes. Alcyonince (purs) Milne-Edwards, Coralliaires. 



In this family the polyps are united together by the Avails or porous coenenchyma 

 throughout nearly their whole extent, forming massive lobed or arborescent clusters of 

 fleshy or coriaceous texture, filled with calcareous spicula. The tentacles and upper free 

 portion of the polyps are capable of more or less perfect contraction. 



This family has been divided by Milne-Edwards into two groups : 1st, Alcyoniens nus, 

 corresponding to Alcyonince of Dana ; 2d, Alcyoniens amies, corresponding to Nephthece Lesson 

 and, in part, to Spoygodince Dana. 



Alcyonium Linn. 



Alcyonium Linnjeus, Syst. Nat., edit. x. vol. i. p. 803, (1758). Mazina Oken, Lehrb. der 

 Nat., t. hi. p. 93, (1815). Lobularia Savigny, (Lamk. Hist, An. sans Vert. 1810) ; Ehrenberg, 

 Corall. des roth. Meer., p. 57, (1834). Alcyonium Dana, Zooph., p. 611, (1840); Milne- 

 Edwards, Coralliaires, t. i. p. 114, (1857). 



Corallum fleshy, filled with granular spicula, which do not project from the surface ; base 

 enlarged, adherent to foreign bodies ; trunk usually destitute of polyps near the base ; above, 



