646 



ZOOPHYTES 



two, have been received by subsequent authors with much hesitation. 

 The thickness of the cortex in the Plexaurae depends simply on the 

 size or height of the polyps, and can hardly be admitted as a charac- 

 teristic sufficiently important even for a subgenus. The occurrence of 

 verrucse is physiologically of as slight importance, as it arises merely 

 from the polyps not being confluent so nearly to their summits. 



Ehrenberg adopted Lamouroux's genera, but mostly under altered 

 or more extended significations, and introduced also the genus Ptero- 

 gorgia. In his system, Pterogorgia and Gorgonia, include the species 

 with bifarious polyps, the first of these genera being distinguished 

 from the other, by having the polyps distinctly in one or two series; 

 Eunicea embraces all the species with scattered polyps, with or with- 

 out verrucaB, and the verruca? unarmed; Muricea and Plexaura have 

 the same limits nearly as above. 



The relations of the several systems are shown in the following 

 table : 



LINNAEUS AND 

 LAMAHCK. 



Gorgonia. 



RECEIVED DIVISIONS. 

 Pterogorgia. 



Gorgonia. 

 Muricea. 



As the genus Gorgonia has been but imperfectly revised, compara- 

 tively few of the species having been seen by the author, the descrip- 

 tions are made out in a less extended form than in other parts of 

 the work. A complete review of the subject has been attempted, as 

 far as it could be done from a thorough study of previous authors and 

 the examination of specimens at hand, and all important information 

 will be found included, together with full references to authorities and 

 figures. 



