COASTS VISITED BY THE AECTIC EXPEDITION - . 589 



Genus Amplextjs, Sowerby, 1802. 



Amplexus Eeildexi, Ether. (PL XXVI. fig. 3.) 



This single incomplete portion of a large Amplexus is, I doubt 

 not, new, and must have been of considerable height or length, 

 judging from the diameter of the corallum left, which measures more 

 than 1| inch. 



Sp. char. Corallum tall, straight, constricted at regular intervals, 

 or where the tabular floors cross the corallum ; septa numerous, 

 equally developed, rather wide apart and marginal ; chief septa about 

 thirty-six in number ; but I cannot be sure that there are not 

 alternately smaller, shorter, or intermediate septa j costae numerous, 

 double the number (seventy-two) of chief septa, thus rendering it 

 probable that there are seventy-two septa (thirty-six primary and 

 thirty-six secondary, comprising two cycles) ; tabulae distant, very 

 slightly concave and smooth, not always of the same size or occupy- 

 ing the same area. JSTow and then the septa on some of the tabulae 

 encroach upon the planes, and thus give them a smaller area ; septal 

 fossula not seen : we have not, perhaps, the last tabulse, in which 

 it is usually more distinct or better preserved. 



This coral is remarkable for its size, the distance between the 

 tabulae, the well- developed costae, the coarseness of the chief septa, 

 and the reed-like habit of its growth, much resembling in appearance 

 many Galamites from the Coal-Measures, especially C. approximatus. 



Many specimens of A. coralloides, Sow., are as large as our A, 

 Feildeni, but differ much in the arrangement and development 

 of the septa upon the tabulas near the edge of the corallite. De 

 Koninck, in his ' Nouvelles Recherches sur les Animaux Fossiles 

 du Terrain Carbonifere de Belgique,' p. 65, t. 5. f. 1, 1872, figures 

 two specimens of A. coralloides equal to, and another double the 

 diameter of, our species ; but the thin disk-like condition of the 

 tabular system entirely removes A. Feildeni from A. coralloides. 

 Numerous as are the species in the Carboniferous rocks of Belgium, 

 still none agrees with our species. 



This and the following species were collected by Dr. Coppinger, of 

 the ' Alert.' 



Loc. Offley Island, lat. 81° 1(3'. Upper Silurian. 



Amplexus, sp. (PL XXVI. fig. 4.) 



I cannot be sure that this is Amplexus Feildeni, although it might 

 pass for a smaller individual. It is of much less diameter, and the 

 costae do not quite agree with those of that species ; the septa are 

 coarser for its size, and range further in upon the tabulae, which, 

 as in Amplexus Feildeni, are also far apart. 



I am not justified in making it a new species. I figure it, how- 

 ever, to draw attention to the form. 



Loc. Offley Island, lat. 81° 16'. Upper Silurian. Collected by 

 Dr. Coppinger. 



