MUSEUM OF COMPARATIVE ZOOLOGY. 9 



GORGONACEA. 



Family CERATOISID^. 



KeratoisidcB + AcanelladcB + Mopseadce (pars) Gray, Cat. Lithophytes Brit. Mus., 



1870, pp. 13, 16, 18. 



Axis simple or variously branched, with long calcareous joints, which are 

 often hollow, alternating with shorter horny joints. Branches, when present, 

 sometimes arise from the calcareous joints, but more frequently from the horny 

 ones. Base calcareous, usually divided into long, flat, irregular lobes, serving 

 as anchors in. the mud of the sea bottom. Coenenchyma thin, commonly with 

 lone fusiform conspicuous spicula, sometimes with small scale-like ones at the 

 surface. Calicles large and prominent, filled with large fusiform spicula, of 

 which ei<fht or more are larger than the rest and commonly project as sharp 

 marginal spines between the bases of the tentacles, forming an armature for 

 the protection of the incurved and imperfectly retracted tentacles. 



This group bears about the same relation to Isidce that Muricea does to 

 Plexaura and Eunicea among the Gorgonians with a horny axis. In typical 

 his the coenenchyma is thick and filled with minute spicula, and the calicles 

 are not prominent nor armed with spines. 



Neither the mode of branching, nor the fact that the branches in some spe- 

 cies arise from the horny, and in others from the calcareous joints, is a sufii- 

 cient reason for separating the very closely allied genera here included into 

 different families, as was done by Dr. J. E. Gray. 



This family includes three well-marked genera that are found on our coast, 

 viz. Ceratoisis, Acanella, and Lepidisis, nov. In addition to these, Callisis 

 occurs in the Straits of Florida. The imperfectly known and not properly 

 characterized genus, Isidella Gray, should probably be referred here, if it be 

 recognized at all. These genera may be arranged as follows: — 



""~ A. Branches arise from the calcareous joints. 



Ceratoisis. Coenenchyma and calicles filled with large fusiform spicula. Cali- 

 cles armed. 



Callisis. Coenenchyma with small oblong scales. Calcareous joints solid, or 

 nearly so. Calicles with fusiform spicula, which do not form long mar- 

 ginal spines. Type, C. Jlexibilis V. (= Isis fiexihilis Pourtales).* 



* Callisis Jlexibilis (Pourt. sp.). The type-specimen of this species has promi- 

 nent, short cylindrical calicles, containing moderately large, rather short, blunt, 

 oblong and fusiform, minutely warted spicula, not running the whole length of 

 the calicles, and projecting very slightly, or not at all, beyond the margin. The 

 coenenchyma is thin, brown, filled with minute oblong or elliptical, flat, scale like 

 spicula, which also cover the surface of the calicles. The branches arise from near 

 the proximal end of the calcareous joints, in the specimen examined. The calca- 

 reous joints, in the several broken branches examined on different specimens, were 

 solid, or rarely had a very minute central tube. 



