128 



horny. In the genera Gorgonella Verrucella and several 

 others the axis is entirely calcareous, as it is in the well 

 known Red Coral ( Corallium.') In Isis, Mopsea, and other 

 related genera it consists of alternate joints or segments of 

 calcareous and horn-like deposits. From these facts it is 

 evident that the character of having a calcareous or horn- 

 like axis is not of so great importance as some naturalists 

 have supposed. Thus Dr. J. E. Gray, has divided the Gor- 

 g-onidce into two sub-orders,'* viz : Lilhophyta character- 

 ized as having a continuous or jointed calcareous axis and 

 Ceratophyta having a horny one. Into the first he puts 

 Primnoa, which, as I have shown, is partly horny , and into 

 the second, Plexaurea, which is partly calcareous. It is 

 therefore evident that such groups are quite artificial. He 

 also has a third suborder called Sarcophyta, which corres- 

 ponds very nearly to the family of Alcypnidce of Dana and 

 Milne Edwards. In this group, if we exclude Briareum, 

 which should go with the Gorgonidce, there is no solid axis 

 and the whole mass is composed of tubular polyp cells 

 united in various ways in the different genera. This group 

 is evidently of higher value than the two other divisions 

 mentioned, and should be placed on a level with Gorgonid& 

 and Ptnnatulidcs, as has been done by both Milne Edwards 

 and Dana. But these three groups, Alcyonidce, Gorgoni- 

 dce and Pennatulicfa, present gradations of structural char- 

 acters which entitle them to be ranked as suborders, rather 

 than as families of the order, Alcyonaria. 



This order as far as yet known is represented on the 

 northern coast of New England, only by Alcyonium carneum, 

 Agassizf and the Primnoa now under consideration. A spe- 

 cies of Leptogorgia is found in Long Island Sound, 

 while farther south the representatives of the order become 

 very numerous. 



The only specimen of Primnoa known to have been pre- 

 viously found on our coast was presented to the Boston Soci- 

 ety of Natural History, in Nov. 1860.$ It was taken in 



* On the arrangement of Zoophytes with Pinnated Tentacles, by Dr. J. E. Gray, 

 Annals and Magazine of Natural History, 3d series, vol. 4, p. 439. 



f On the structure of the Halcyonoid Polypi. By Louis Agassiz. Proceedings of 

 the American Association for the Advancement of "Science, 1850. 



{Proceedings of the Boston Society of Natural History, Vol. 7, p. 418. 



