646 
ME. P. MAETIN DUNCAN ON THE GKENEEA HETEEOPHYLLIA, 
6. Heterophyllia Lyelli, sp. nov. Plate XXXI: figs. 4 a- 4 c. 
The corallum is very long, very slender, and is slightly bent. The costae are large, 
smooth, and rounded; they project and are marked with occasional tubercles, pits, and 
grooves. The intercostal spaces are wide, shallow, and equal ; they are slightly concave, 
and are marked with festoon-shaped ridges or lines. The horizontal section of the 
corallum is hexagonal in outline ; the wall is stout and thick, and only very slightly 
concave between the costse. The surface of the corallum is smooth and plain. There 
are six septa, which are united by a linear septal columella. The endotheca is tolerably 
abundant. The diameter of the corallum is y^ inch or less. 
In the Carboniferous limestone of Craigenglen, Stirling, and Brockley, Lesmahagow, 
Lanarkshire. 
7. Heterophyllia mirabilis, sp. nov. Plate XXXI. figs. 5 h. 
The corallum is tall, very slender, and nearly straight. The costae are narrow, rounded, 
smooth, and slightly projecting; they have tubercles at regular and frequent intervals. 
These tubercles are rounded and oblique, and project slightly. To each of them is arti- 
culated a curved hook-shaped process, which stands out from the costa and the tubercle, 
its concavity being directed inwards and downwards. The intercostal spaces are shallow, 
wide, and usually slightly convex, but occasionally concave ; they are marked with three 
longitudinal delicate shallow grooves with very slightly rounded longitudinal eminences 
between them. A groove is central. The horizontal section of the corallum is nearly 
circular; there are projections which correspond with the costae; and the wall is mode- 
rately thick. The surface of the corallum is smooth. There are six septa, which are 
united by a linear septal columella. The endotheca is scanty, and the dissepiments are 
wide apart. The diameter of the corallum is rather more than inch. 
From the Carboniferous limestone of Craigenglen and Brockley. 
8. Heterophyllia Sedgwicki, sp. nov. Plate XXXI. figs. 6 a - 6 e. 
The corallum is tall, thin, and very flexuous, except near the calice, where it becomes 
straight. The costae are numerous, small, very slightly projecting, rounded, unequal, 
distant, and flexuous ; they are grooved, and vary in number, eighteen or nineteen being 
the maximum. The intercostal spaces are shallow, rather wide (but occasionally narrow), 
slightly convex, and grooved longitudinally ; and the appearance of false costae is thus pro- 
duced. The horizontal section of the corallum is nearly circular in outline ; the wall is 
thin, and the costae project very slightly. The surface near to the calicular end is coria- 
ceous, and over the rest of the corallum it is smooth. The septa are twenty in number. 
There are ten large and ten small septa in the calice. In sections there are eighteen or 
nineteen very irregular septa ; all the larger radiate to the centre. The calice is regular, 
and there is a small columella (a septal). The reproduction is partly by gemmation 
around the calice at the end of the stem-like corallum. The buds have many septa. 
The endotheca is very abundant, and the wall is thin. The diameter of the corallum 
is from y^ to yj inch ; and the calicular end, with its buds, measures in diameter yg- inch. 
In the Carboniferous limestone of Brockley, Lesmahagow, Lanarkshire. 
