•"IjmmluCl'eb^'ri^m'] ^oyol Mieroscopieal Sociekj. 91 



Phyllogorgia. — Polypary explanate, foliaceous ; the sclerobasic 

 axis branching, and the more slender ramifications anastomosing 

 frequently among themselves, as with the genus Rhipidigorgia, 

 the ccBnenchyma, however, not constituting a cylindrical cortex 

 around the axes, but expanding laterally, so as to form large 

 foliaceous lamina, on the surfaces of which the calices are disposed. 



In P. dilitata the Leptogorgian and scaphoid types of spicula 

 predominate. Phyllogorgia foliata is described as closely approxi- 

 mating the last-named species ; but I have not yet had an oppor- 

 tunity of examining its spicula. 



Hymenogorgia. — The only diiference existing between this 

 genus and the last is, that the minor ramifications of the sclero- 

 basic axis do not coalesce. The coenenchyma forms similar 

 foliaceous expansions, and the spicula follow essentially the same 



Phycogorgia. — In this genus the sclerobasic axis itself becomes 

 dilated in membranous expansions, resembling a fuciis invested 

 with a slender and porous coenenchyma. One form of spicula 

 alone is represented in the single species, P.fucaia, and that the 

 regular Leptogorgian type. 



The four next genera have been separated by Milne Edwards 

 into a distinct group, the Gorgonellacess, on account of the 

 sclerobasic axis containing a large amount of calcareous in addi- 

 tion to corneous matter; he considers, however, that they respec- 

 tively correspond to certain genera of the Gorgonaeese (M. Edw.) 

 possessing entirely corneous axes. KoUiker, as has been already 

 observed, has made, partly for the same reason, a similar se2)aration 

 of several species from Plexaura, creating for them the new generic 

 title of Plexaurella. 



Gorgonella. — Polypary much branching ; sclerenchyma very 

 slender ; calices httle or not at all prominent. Milne Edwards 

 considers this genus equivalent to Lejjtogorgia ; the spicula, more- 

 over, of G. sarmentosa, the only species I have yet examined, are 

 not distinguishable from the type predominant in the last-named 

 genus. 



Vernicella. — The author just quoted regards this genus as 

 corresponding with Gorgonia proper. The polypary is arborescent, 

 the sclerenchyma moderately thick, and furnished with exceedingly 

 prominent cahces. In correlation with the above, it is a significant 

 fact that the spicula of Verrucella gemmacea agree, to a certain 

 extent, with the form characteristic of Gorgonia verrucosa and 

 its alhes, possessing a modification of the lagenate type (Plate XLIL, 

 Figs. 27, 28) ; the attenuato-fusiform is, however, not represented 

 but replaced by a form best described as the spiked dumb-beU type 

 (Plate XLIL, Fig. 29). 



Plexaura nodidifera, M. Edw. {Gorgu)iia, Lamk.), possesses 



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