134 CCELENTERATA 



teries, tliat wliicli looks towards the siplionoglypli. The skeleton con- 

 sists of calcium carbonate or ceratine sjiiculcs imbedded in the mesoglea, 

 but formed by cells of edodermic origin, which may be fused together in 

 the center of the colony so as to form a compact axis: in a few genera 

 a skeleton is lacking. The mesoglea, stiffened thus by the spicules, 

 together with the outer ectoderm, is called the coenenchym. The polyps 

 are seated in depressions in the coenenchym, into which they can usu- 

 ally retract, and are in communication with one another by means of 

 entodermal canals (Fig. 222, B). The Alcyonaria are often brightly col- 

 ored and phosphorescent and are among- the most conspicuous objects in 

 the tropical seas. The order contains about 33 families and over 600 living 

 species, grouped in 5 suborders. 



Key to the suborders of Alcyonaria here described: 



a^ Colony fixed and stationary. 



hi Polyps rise from a stolon 1. Stolonifera 



^2 Colony erect. 



Ci Central skeletal axis absent 2. Alcyonacea 



Cn Central skeletal axis present 3. Gorgonacea 



02 Colony not fixed or stationary 4. Pennatulacea 



Suborder 1. STOLONIFERA. 



Colony consists of independent polyps which rise from a mem- 

 branous or ribbon-like stolon; they are not continuously joined but may 

 be united by transverse tubes or plates: 3 families. 



Family COENTJLARIIDAE. 



Polyps not joined together except by the creeping stolon from which 

 they spring ; spicules usually absent : about 15 genera. 



CoRNULARlELLA Verrill. Upper portion of polyp retractile into the 

 rigid lower portion; spicules present: 1 species. 



C. modesta Vei-. Polyps G to 18 mm. high and 3 mm. in diameter; 

 color of stolons and loAver part of polyps yellow or brown : Casco Bay to 

 Gulf of St. Lawrence, from 30 fathoms to deep water. 



Suborder 2. ALCYONACEA. 



Colony usually branching, without central axis; coBnenehym with 

 spicules and usually fleshy: about 10 families and over 100 species. 



Family 1. ALCYONIIDAE. 



Colony simple or branching and more or less massive; polyps elon- 

 gate and joined by . entodermal canals ; coenenchym with numerous 

 spicules: about 12 genera. 



Alcyonium L. Colony composed of short, thick lobes and soft or 

 leathery; polyps long and, with the exception of the outer end with the 



