146 THE VOYAGE OF H.M.S. CHALLENGER. 
with specimens of Deltocyathus italicus, kindly given to me for the purpose by Count 
Salvadori, of Turin, I considered that Pourtalés was quite justified in maintaining 
Deltocyathus agassizi as a separate species, on the grounds of the structure of the 
costee ; but I have, at the moment that this memoir is going to press, learned by a letter 
from Count Pourtalés that he has been led, by the examination of a long series of speci- 
mens dredged this year by Mr Agassiz, to the conclusion that the specific claims of 
Deltocyathus agassizi cannot be upheld, and that he intends to adopt for the American 
form the old name, as Professor Martin Duncan had already done. I have, therefore, 
done so also. 
I give here woodcuts of the more usual form of the species, and of Pourtalés’ variety 
calcar, from drawings by Mr J. J. Wild. 
Although the series obtained near St Thomas, Danish West Indies, appeared to bear 
out Pourtalés’ assertion that the young coralla of this species are cup-shaped, and 
that they gradually become more saucer-shaped as age advances, such is not the case in a 
long series of fifty specimens dredged off the Azores. In this nearly all the larger speci- 
mens have the calicle deeply cup-shaped, whilst the younger ones are flatter, and some of 
the very small ones (2°5 mm. in diameter) absolutely flat. Some of the specimens are 
14 mm. in diameter, a shade larger than Pourtalés’ largest specimen. The series 
presents points of well-marked variation from the West Indian specimens. The coralla 
are all characterised by having their primary and secondary septa, as well as their pali, 
extremely exsert; but the pali never project so high as the septa to which they are 
soldered at their bases, as they doin Pourtalés’ specimens and in those dredged by the Chal- 
lenger in the West Indies. No tendency towards the development of the horned variety 
described by Pourtalés is to be seen in the series obtained off the Azores, although Pro- 
fessor Lindstrém remarks on an approach to the variety calcar in some of his East 
Atlantic specimens, as shown in them by an excessive development of the primary costee. 
It is remarkable that only one specimen of the horned variety was obtained by us, and 
that (the one figured) merely by accident, in the cup of a sounding machine off Bermuda. 
It is further very remarkable that none of the specimens obtained by us were attached, 
and that only one shows any trace of ever having been attached. This one specimen, 
however, is large, and though somewhat imperfect has a most distinct pedicle and scar of 
attachment, and evidently remained fixed up toa period of full maturity. It is figured on 
Plate II. figs. 2, 2a, 2b. Since, singularly enough, none of Count Pourtalés’ specimens 
were attached, or showed traces of attachment, I figure (PL II. figs. 3, 3a) a specimen, 
one of two kindly sent to me for examination by Professor Lindstrém, and dredged off 
the Danish West Indies in from 200 to 320 fathoms. There can be no doubt as to the 
identity of this specimen with D. agassiz. 
After comparing Professor Martin Duncan’s specimen of Sabinotrochus apertus with 
the series of Deltocyathus, I conclude that Professor Lindstrém’s conjecture that it is a 
