296 



Dr. P. Martin Duncan on the 



[Mar. 24, 



simple perforate coral were dredged up in lat. 59° 56' N., long. 6° 27' W., 

 363 fathoms, temperature 31°"8 (No. 54), and one in lat. 61° 10' N., lon». 

 2° 21' W., 345 fathoms, temp. 29°'9 (No. 65). 



The six specimens are of different sizes and ages ; and although thev 

 present considerable variation in shape and septal development, they evi- 

 dently belong to one type. The solitary coral from Xo. 65 is larger than 

 the others, but it belongs to the same species. 



Notwithstanding the temperature in which the corals were found, and 

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

 an active and abundant nutrition. 



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

 psammice of Pourtales. 



Thecopsammia socialis, 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 Floridan type, found at greater 

 depths, and doubtless in much colder water, present evidences of greater 

 vigour than the American forms. They are larger and denser, and their 

 septa are better developed. Moreover some of them, although thev 

 possess all the other characteristics of the genus as diagnosed by Pourtales, 

 present indubitable costae, 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 well-known Balanophyllice and the new Thecopsammia: very 

 unstable. The Thecopsammice, from the peculiarities of their wall, epitheca, 

 aud septa, well merit the distinction of a subgenus ; and therefore I propose 

 to restore the species associated under the term to the genus BalanophyUia, 

 in the subgenus Thecopsammia. 



BalanophyUia {Thecopsammia) socialis, Pourtales, var. costata. No. 54, 

 1 Porcupine ' Expedition. 



( ) , var. britannica. No. 54, ' Porcupine ' Expedition. 



( ) , var. Jeffreysia. No. 65. 



All these varieties refer to specimens which were fixed by their bases to 

 stones. 



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

 genus BalanophyUia. They have only a very remote affinity with the 

 West-Indian recent BalanophyUia;, with those of the Crag, the Faluns, and 

 the Eastern Tertiaries. 



The British forms appear to have emigrated 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 northern sea, where 

 they have propagated, varied, and thriven. 



