CRisiiiJ.1-:. 417 



Family I. Crisiidae. 



LKS CKIBIES, Milne- Edwards. 



CKI.SIAD.E, Johnston &c. 



CBISID.K, D'Orbigny. 



CRISIIDA, Busk. 



CKISIE.E, Sinitt. 



CIMSIDEA, Reuse, Bryox. d. deutech. Sept. 



ZOARIUM dendroidy calcareous, composed of segments united 

 by corneous joints. ZCKECIA tubular, disposed in one 

 or two series. 



IN this family the polypide is small and of a simple 

 type. When it is expanded, only the crown of tentacles 

 protrudes beyond the opening of the cell; when re- 

 tracted, the body is not doubled upon itself, but hangs 

 straight within the cavity. There is no gizzard ; the 

 structure of the alimentary canal is perfectly simple. 

 The number of the tentacles is eight ; and they are clothed 

 with extremely minute cilia. 



The colony originates in a small disk-like body, with a 

 calcareous covering, from which the primary cell is deve- 

 loped, jointed at the base. From the sides of the disk 

 radical fibres are given off, which spread in all directions, 

 attaching themselves to the base on which the colony is 

 planted ; these fibres are also jointed at intervals, and 

 more or less branched. Besides these primitive rootlets 

 other organs of attachment exist, in the shape of long 

 fibrils, which originate at the base of the internodes, and, 

 tending downwards, become adherent by means of lateral 

 offshoots and serve as buttresses to the colony. On the 

 lower portion of the shoot these fibrils arc often extremely 

 numerous, as many as four or five proceeding from a 

 single internodc. They are divided into segments by 



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