THE ALCYONID& 



306 



has a large quantity of carbonate of lime in its stem, and it is interesting to note the repetition 



of external form, in this division, of that noticed amongst the corneous-stemmed forms. It is 



the genus Gorgonella, and it corresponds to the Leptogorgias in the last division, but the axis 



is very calcareous, and Verucella has the configuration of the Gorgonia?. One genus, Juncella, has 



a simple, non-branching, straight stem, like a stick, and the polypes project slightly. It has been 



found in the Mediterranean, off 



Bahia, and on the east coast of 



Africa. The last group is that 



of the Briaracese, in which the 



axis, or stem, is no longer dense, 



solid, and concentric, but may 



be hollow or a mere mass of 



spicules. Briareum is the typical 



genus, and Paragorgia is its most 



important ally. 



THE FAMILY ALCYONIDJE. 



With the exception of one 

 genus, this great family is 

 characterised by the absence of 

 anything like a continuous 

 skeleton or supporting dense 

 hard structure. In no case is 

 there an axis, as in the Red 

 Coral and Gorgonias, but there 

 is much soft structure, in which 

 isolated calcareous sclerites or 

 spicules are placed, sufficient to 

 detract from a perfect con- 

 tractility and softness. Hence some are leathery or fleshy. The polypes are fashioned after the 

 Alcyonarian type, have eight pinnate tentacles, and their visceral cavity has membranes in it sup- 

 porting the reproductive elements. The soft tissues, or ccenosarc, contain the polypes, whose centres 

 communicate with a common series of minute canals. Many forms increase by budding, some from 

 the base and others from the sides, and thus two sub-families, the Cornularinse and the Alcyoninse, 



can be established. There are 

 some forms, however, which pro- 

 duce a wall of calcareous spicules 

 and a kind of corallum, and thus 

 a third sub-family, the Tubi- 

 porina?, is formed. This is a very 

 exceptional form, and the rest 

 are fixed by their fleshy bases. 

 Where the polypes are in con- 

 siderable numbers and surrounded 

 : by a ccenosarc, they extend deeply, 

 and as they are produced by 

 TUBIPOHA MCSICA (ORGAN-PIPE CORAL). budding they may have their 



visceral cavities elongate and 

 either in the direction of the lower sides or of the whole mass. Some are very retractile. 



The Organ-pipe Coral * forms very considerable masses of a deep red colour, and is found in the 

 Red Sea and the Pacific. Its appearance is very familiar to visitors to museums, and it is made up, 

 in the dry and the dead state, of a multitude of small cylindrical tubes placed in rows one over the 



* Tubipwa musica. 



SEA FAX (Gorgonia flabellum). 



