ON THE STRUCTURE OF CERATELLA FUSCA (grAy). 19 



(4.) The gonophores of the Ceratelladae arise directly from the ccenosarc 

 and are not developed on special zooids as in the case of the 

 Hydractiniidfe. 



Whilst the points of agreement detailed ahove serve to show a general 

 resemhlance between the members of the two groups those of difference are of 

 snfifieient importance to justify tlieir separation into two distinct families. 



As stated previously Dr. Gray's name Ceratelladae will be retained and the 

 following gives the characters of the family (moditied from Dr. Gray's and Messrs. 

 Garter and Bale's descriptions) and tlie list and characters of the genera and species 

 yet known. 



Family Ccratclladcv (Gray, Proc. Zool. Soc, 1868, p. 575). 



Forming branching colonies. Skeleton in the form of a chitinous network with 

 slight bracket-like or tubular projections (hydrophores) serving as a support for the 

 bases of the gastrozooids. 



Hydrophyton a network of branching anastomosing tubes the whole enclosed by 

 a common ectoderm layer. 



Gastrozooids naked. 



Gonophores medusoid : fixed and arising directing from the hydrophyton. 



Genus. Dehitella. (Gray.) 



Colony dichotomously branched, expanded growing in a large tuft from a broad 

 creeping base. Stem cylindrical, smooth ; branches tapering and cylindrical. 

 Hydrophores slightly tubular and on the smaller branches divergent nearly at right 

 angles from the stem. 



(1.) Dehitella atroriibens. (Gray.) 



The description of the species is the same as that of the genus. It is known at 

 present simply from that given by Dr. Gray* who states that the genus " is 

 distinguishable from Ceratclla by the greater thickness and cylindrical form of the stem, 

 by the more tufted and irregular manner of growth and by the tufts of spicules (oscules 

 or cells) being more abundant and equally dispersed on all sides of the branches and 

 branchlets." The " oscules or cells " of Dr. Gray must be the structures which, 

 following Mr. Bale, have been described above as " hydrophores." 



Locality. — Delagoa Bay, Africa. 



• Proc. Zool. Soc. 1868, p. 579. Fig. 1. 



