REPORT ON THE ALCYONARIA. xxxix 



Dasygorgidse 

 I 



Isidae PrimnoidiE Muriccidae 



I 

 Plexauridap 



I . 

 (JorgonidsB 



I 

 Gorgonellidoe 



Family V. D a s y G o R G i d ^. 



In the species of this family the colonies are simple (jr branched, with a horn)- 

 calcareous axis ; the coenenchyma is thin and the polyps are large and distant from one 

 another ; the polyps are not retractile, and in rest simply curve their tentacles over the 

 oral apertures. Both the coenenchyma and polyps contain simple smooth calcareous 

 needle-like or spindle-like spicules, or semi-opaque scales which are continued on to the 

 tips of the tentacles. 



The Dasygorgidse represent in many ways the simplest type of Holaxonia. The axis 

 is either simple, rod-like, and unbranched, or else ramified in such a way that from the 

 main axis lateral branches are given off, which may again bear twigs. Tlie axis springs 

 from a calcareous basis which is sometimes ramified in stolon-like processes and sometimes 

 becomes a simple flatly expanded disc. The axis itself is composed of a fibrous horny 

 substance, with iuterstratified calcareous particles. The latter is most abundant towards 

 the base, less so towards the ends of the stem, l)ranclu's, and twigs, the terminal twigs being 

 horny. The surface of the axis and branches is smooth and shining, and often exhibits 

 a golden or iridescent appearance. The coenenchyma is in most cases very thin. The 

 polyps are large, often of greater diameter than the branch on which they are seated, 

 and usually occur in a single row on the stem and branches. Their structure is simple ; 

 calyx, oesophageal, and tentacular portions are never well differentiated. A layer of 

 calcareous spicules extends from the base of the polyp to the tips of the tentacles, leaving 

 only the pinnae free. When at rest the tentacles are simply folded over the oral disc. 

 Besides the tentacle-bearing polyps (autozooids), very small conical shaped pol}^s (siphono- 

 zooids) occur in many s^iecies. These exhibit a capitate apex filled with nematocysts, and 

 under this the cleft-like oral cavity. The canalicular system consists of four longitudinal 

 canals, which extend along the axis, and directly receive the eight canals issuing from eacli 

 polyp form. The sjiicules in the ca>nenchyma and polyps are simple smooth needles, or 

 spindles, or scales which are often dentate at their margin and have a hyaline appearance. 



The first described genus of this family was Herophila, Stecnstni[> ; tliose which 

 Duchassaing and Michelotti' described under the titles Chrysogorgia and Riisea 



' Alemoire sur Ics Coral, des Antilles, 1860, Suppl., p. 21, pi. iv. fig. 5. 



