448 POLYPI. 



In the third tribe, or the 



Nat ANTES, 

 The axis is stony but not fixed. 



Pennatula, Lin., 



A common body, free from all adhesion*, of a regular and constant 

 form, and susceptible of locomotion by the contractions of its fleshy 

 portion and the combined action of its Polypi. This body is fleshy, 

 and contracts or dilates in its various parts by means of the fibrous 

 layers that enter into its composition ; its axis encloses a simple stony 

 stem ; the Polypi have generally eight dcntated arms. 



Most of the species dirt^use a vivid phosphorescent light. 



Whatever be the general form of the Pennatula?, one of their ex- 

 tremities is always destitute of Polypi, and has been compared to the 

 tubvdar portion of a bird's feather. 



Pknnatula, Cuv. 

 The Pennatulse, properly so called, have given their name to the 

 whole genus, which name has been derived from their own resem- 

 blance to a quill. The portion destitute of Polypi is cylindrical and 

 terminates in an obtuse point. The other part is furnished on each 

 side with wings or laminae, more or less long and broad, supported 

 by spines or rigid setse which arise from their interior and roughen 

 one of their edges, without, however, being articulated Avith the 

 stony stem of the axis ; it is from between their laminae that the 

 Polypi protrude. 



P. rubra, P. phosphorea, Gm.f; Albinus, Annot. Acad., I, 

 vi, 3, 4. Where the stem between the laminae is extremely 

 scabrous posteriorly, with the exception of a longitudinal line. 

 In the Atlantic ocean and Mediterranean. 



P. grisea, Gm.; Albinus, Annot. Acad., I, vi, 1, 2. Larger, 

 with broader and more spinous laminae; stem smooth. More 

 particularly in the Mediterranean:!:. 



ViRGULARiA, Lam. 



The Virgulariae only differ from the Pennatulse in their wings, 

 which, much shorter in proportion to their total length, are destitute 

 of spines §. 



These wings sometimes merely represent transversal ranges of 

 tubercles II . In 



little importance, see the " Exposition Methodique ties genres des Polyjnei'S, avec les 

 planches de Solander et Ellis," by Lamouroux. Paris, 1821. 



* Certain species penetrate into the sand or become entangled in the folds of va- 

 rious marine bodies, but never form any durable adhesion. 



t Both are red. The P. rubra only differs from the other in having a little spine 

 at the base of each posterior lamina. It is perhaps a mere variety. 



X Add Pennahda argenfea, Sol. and Ell., Zooph., VIII, 1, 2, 3; — P. grandis. 



§ Pennatula mirabilis, Miill., Zool. Dan., XI, very different from the true Pennat. 

 mirabilis of Linnaeus. 



II Pennatula juncea, Pall, and Gm. ; also very different from the P. mirabilis, L. 

 The Virgulaire australe, Lam., does not differ from the juncea. 



