MADREPORARIA OF THE DEEP SEA. 325 
on the Corals of the First ‘ Porcupine’! Expedition, respecting the very close alliance 
of Amphihelia and Lophohelia consistent with facts I have observed since. I find that 
there are never any dissepimental structures developed in Amphihelia, whilst they exist 
and even take up the tabulate form in many specimens of Lophohelia. 
The absence of the columella, in all the specimens of Amphihelia 1 have seen, is very 
rare indeed; and as the structure is never observed to be wanting in many consecutive 
corallites on a stem (for even at the worst the large septa join centrally), the want of 
the organ may be an arrest of development. 
Every now and then the third cycle of septa is so very rudimentary in Amphihelia 
oculata, Linn., that doubts may be expressed about its existence; yet in the same 
corallum it may be visible in remote calices, 
The existence in Amphihelia of well-developed spongy and trabecular columelle, of 
very small columellz of the same consistence, and of those formed by a swollen state 
of the inner and adherent margins of the larger septa is beyond doubt. 
The ornamentation of the coste and their general development afford specific 
distinctions. 
By grouping the specimens obtained from the first and second expeditions of the 
‘Porcupine, the following series may be distinguished :— 
1. Columella moderately developed. 
Septa in two cycles, first and second equal, the third cycle either very rudimentary 
or wanting. 
Surface of wall plain. Coste very fine, and serpentine near the newest calices. 
2. Columella very small. 
Septa in three cycles, first and second unequal. Septa dentate. 
Surface plain. 
3. asno. 2. Surface minutely and sharply granular. 
4. as nos. 2 & 3. Coste fine and visible near the calices. 
5. Columella moderately developed. 
Septa in three cycles. 
Surface marked by continuous costal strie. 
6. Columella very small. 
Septa in three cycles, tertiary dentate. 
Surface marked by continuous and noncontinuous costal strie, and covered with 
granules. 
7. as no 6. 
Surface strongly striated. Septa not dentate. 
8. Columella small. 
Septa in three cycles: the primaries are often exsert. 
Surface of wall plain. Costal striz near new calices. 
1 Proc. Royal Society, 1870, P. M. Duncan. 
