448 Young — On the Genus Heterophyllia, 



III. — On the Identity of Heterophtllia Lyelli and H. mirabilis 



OF Duncan. 



By John Young, Curator of the Hunterian Museum, Glasgow. 



IN a paper published in the Proceedings of the Eoyal Society 

 of London,^ Dr. Duncan has figured and described six new 

 species of Carboniferous corals, belonging to the genus Hetero- 

 pht/llia of M'Coy, from specimens found in Scottish Carboniferous 

 limestone strata. Of these species two H. Lyelli and H. mirabilis, 

 seem to be founded on portions, which the careful examination of 

 better preserved specimens would have shown to belong to only one 

 good species. 



I would not have ventured to make the following remarks upon 

 these corals, had not the localities from whence they are obtained 

 been long and familiarly known to me ; and I am satisfied, after a 

 careful examination of more than 50 specimens, large and small, and 

 in all states of preservation, that they all belong to one species, in 

 which the external characters and internal structure vary to a 

 certain extent. 



In order to show the close connection that exists between these two 

 so-called species, I will quote Dr. Duncan's description of the corals, 

 side by side, with the parts numbered, so that the points of specific 

 distinction may be more easily perceived, and will then make my 

 remarks in support of what I consider their identity. 



Heterophyllia Lyelli, sp. nov., Duncan. Heterophyllia mirabilis, sip. hoy., DvLncan. 

 1st. The corallum is very long, very 1st. The corallum is tall, very slender, 



slender, and is slightly hent. and nearly straight. 



2nd. The costse are large, smooth, and 2nd. The costse are narrow, rounded, 



rounded ; they project, and are marked smooth, and slightly projecting ; they 

 with occasional tubercles, pits, and have tubercles at regular and frequent 

 grooves. intervals. These tubercles are rounded 



and oblique, and project slightly. To 

 each of them is articulated a curved 

 hook-shaped process, which stands out 

 from the costa and the tubercles, its con- 

 cavity being directed inwards and down- 

 wards. 

 3rd. The intercostal spaces are wide 3rd. The intercostal spaces are shallow, 



and shallow, and equal ; they are slightly wide, and usually convex, but occasionally 

 concave, and are marked with festoon- concave ; they are marked with three 

 shaped ridges or lines. longitudinal delicate shallow grooves, 



with very slightly rounded longitudinal 



eminences between them. A groove is 



central. 



4th. The horizontal section of the 4th. The horizontal section of the 



corallum is hexagonal in outline ; the corallum is nearly circular ; there are 



wall is stout and thick, and only very projections which correspond with the 



slightly concave between the costa?. costae ; and the wall is moderately thick. 



6th. The surface of the corallum is 5th. The surface of the corallum is 



smooth and plain. smooth. 



^ On the Genera' Heterophyllia, Battersbyia, Palceocyclus, and Asterosmilia ; the 

 Anatomy of their Species, and their position in the Classification of the Sclerodermic 

 Zoantharia. By P. Martin Duncan, M.B. Loud., F.G.S., Secretary to the Geological 

 Society. — Read May 2, 1867. 



