74 GORGONIA. 



at one time of the year than another, and in proportion 

 to a certain temperature of the air, like other fixt ani- 

 mals ; for inftance, oyfters, which we obferve at certain 

 feafons producing a new fhelly ffratum, or layer, next to 

 the flefli in the infide of their upper and under mell : 

 indeed, in many of the Gorgonias their feveral layers of 

 hard parts, or bone, are very like thofe of fhells both in 

 their confiftence and polifhed mining quality. This 

 is remarkable in the Gorgonia verticillata. See Tab. 2. 

 fig. 4. where there is a fmall trunk of its natural fize, 

 and the top of it magnified at fig. 5. to mew the fliell- 

 like difpofition of the laminae. 



As I have endeavoured to prove that there is no com- 

 munication between the circles in the bony part of the 

 Gorgonia, fo it is evident there is none between the la- 

 minae or layers of the oyfter-fhell ; becaufe we often find 

 them bored all over by fea infects, and yet if the inner- 

 moft lamina next to the fifli is found, the animal is 

 found to be in perfect health and vigorous, as I have often 

 experienced. 



But perhaps the formation of the bony part of the Gor- 

 gonia, and the nature of the connection of the different 

 circles of laminae, of which they are compofecfc, may be 

 more naturally and fatisfactorily illuftrated by examining 

 the bony part of the Pennatulas, or Sea-Pens, a genus of 

 Zoophytes not far removed from the Gorgonias, on ac- 

 count of their polype mouths, as well as having a bone in: 

 the infide, and flefli without. One of the chief differ- 

 ences is, that as the Gorgonias are always fixt,. there is a 

 neceiiity, that in order to keep them firm in their places 

 they fliould be fpread out at the bafc, both in the bony as 

 well as fleihy parts ; whereas the Pennatula, or Sea-Pen , 

 which is made for fwimming about in the fea, has its 

 , bone 



