Simpson — A Revision of the Gorgonellidae. 253 



dilTeieiit specimens, so that it is almost ceilain that in this group the colonies 

 are dioecious. 



IV. — Historical Summary of the Group. 



Family GORGONELLIDAE. 



Tlie family Gorgonellidae is here regarded, on the whole, in the sense of 

 Wright and Studer (L, p. Ixiv), who, accepting Kolliker's diagnosis, define 

 it in the following terras : — 



" In the species of this family the eoenenchyma is thin, smooth on the 

 surface, with small spicules in the form of warty double-clubs and stellate 

 forms. The polyps have more or less well-developed verrueae and are usually 

 biradially disposed. The axis is lamellar and calcareous, but retains its 

 shape after the extraction of the calcareous matter." 



The colonies in the Gorgonellidae form simple or branched masses whose 

 calcareous axis gives to the whole a rigid appearance. The branches and 

 twigs are frequently flattened ; and the polyps are either distributed in two 

 rows on the edges thereof, or are so disposed in lateral bauds that a free 

 space is left in the middle, in which are to be found one or more longitudinal 

 furrows. The longitudinal canals are partly of small diameter, partly large. 

 Two usually occur on the surfaces of the stem which are destitute of polyps. 

 On the surface of the eoenenchyma in dried specimens their position is 

 marked by longitudinal grooves. 



It includes the following genera: — 



NiCELLA, . , . . Gray. 



SciRPEARiA, .... Cuvier, emend. Studer. 



SciRPEARELLA, . . . Wright and Studer. 



JuNCELLA,' .... Valenciennes, emend. Studer. 



Ellisella, .... Gray, emend. Studer. 



Verrucella, . . . Milne-Edwards. 



Ctenocella, . . . Valenciennes. 



Phenilia, .... Gray. 



Heliania, .... Gray. 



The two genera Phenilia and Heliania are only imperfectly known ; and 

 the diagnoses, as given by Gray, leave much to be desired. Studer considers 

 Phenilia as synonymous with Gorgonella ; and it is more than likely that 

 Heliania cannot now be considei'ed as a distinct genus. The spicules of 



' Tlie oiigiiml spelling of this genus was " Junceella," but it is now generally written " Juncella," 

 80 that, except in references, the more common spelling has been adopted in this report. 



