On tite ' Porcupine ''-Expedition Maclreporaria. 293 



Notwithstanding; the temperature in which the corals were found, 

 and the depth of the sea, they ore strong and well- developed forms, 

 evidencing an .active and abundant nutrition. 



There is no difficulty in classifpng the specimens with the Theco- 

 psammke of Pourtales. 



Thecoj^sammia social is, Pourtales, was dredged up in from 100 to 

 300 fathoms, off Sombrero, near Florida, in the course of the Gulf- 

 stream. 



I have been able to compare the specimens dredged up in the 

 ' Porcupine' Expedition with M. Pourtales's types, and, after making 

 due allowance for variation, I have no doubt about including the 

 British forms under his specific term. These varieties of the Flo- 

 ridan type, found at greater depths, and doubtless in much colder 

 water, present evidences of greater vigour than the American forms. 

 They arc larger and denser, and their septa are better developed. 

 Moreover some of them, although they possess all the other charac- 

 teristics of the genus as diagnosed l)y Pourtales, present indubitable 

 costa), especially inferiorly. This clinging to the Balanophyllian 

 type is not witnessed in the Floridan forms ; but it is too important 

 to be passed over, especially as it renders the generic distinction 

 between many wcll-]i.nowa Balano2)hi/lli(v and the new Thecopsanimice 

 very unstable. The Thecopsammia', from the peculiarities of their 

 wall, epitheca, and septa, well merit the distinction of a subgenus ; 

 and therefore I propose to restore the species associated under the 

 term to the genus BaJanophyllia, in the subgenus Tliecopsammia. 



BalanophylJia (Tliecopsammia) socialis, Pourtales, var. costaia. No. 

 54, ' Porcupine' Expedition. 



( ) , var. hntannica. No. 54, 'Porcupine' Expedi- 

 tion. 



( ) , var. Jeffreysia. No. G5. 



All these varieties refer to specimens wliich were fixed by their 

 bases to stones. 



The varieties and the original types are very isolated forms in the 

 great genus BaJanophyllia. They have only a very remote affinity 

 with the West-Indian recent BalamiJiyllia', with those of the Crag, 

 the Ealuns, and the Eastern Tertiaries. 



The British forms appear to have emi,--rated from the south-west ; 

 and probably the original type wandered through the agency of the 

 Gulf-stream, which carried the ova and deposited them in our north- 

 ern sea, where they have propagated, varied, and thriven. 



Pliobothrus symmctricus, Pourtales. — A specimen of this doubtful 

 coral (which had been described by M. de Pourtales from the results 

 of dredging in from 100 to 200 fathoms) was sent to me by Dr. Car- 

 penter. It came from the cold area, in from 500 to 000 fathoms. 



There is no doubt that this very polyzoic-looking mass belongs to 

 the American type. The tabular are hardly worthy to be called such ; 

 and I place the form amongst the Zoantharia provisionally. 



III. The species of Maclreporaria belong to genera which do not 

 contribute and have not contributed to form coral-reef faunas. None 



