146 THE VOYAGE OF H.M.S. CHALLENGER. 



with specimens of Dcltocyathus italicus, kindly given to me for the purpose by Count 

 Salvador^ of Turin, I considered that Pourtales was quite justified in maintaining 

 Dcltocyathus agassizi as a separate species, on the grounds of the structure of the 

 costae ; but I have, at the moment that this memoir is going to press, learned by a letter 

 from Count Pourtales 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 Pourtales' variety 

 calcar, from drawings by Mr J. J. Wild. 



Although the series obtained near St Thomas, Danish West Indies, appeared to bear 

 out Pourtales' 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 Pourtales' 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 do in Pourtales' specimens and in those dredged by the Chal- 

 lenger in the West Indies. No tendency towards the development of the horned variety 

 described by Pourtales is to be seen in the series obtained off the Azores, although Pro- 

 fessor Lindstrom 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 costas. 

 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 to a period of full maturity. It is figured on 

 Plate II. figs. 2, 2a, 2b. Since, singularly enough, none of Count Pourtales' specimens 

 were attached, or showed traces of attachment, I figure (PL II. figs. 3, 3«) a specimen, 

 one of two kindly sent to me for examination by Professor Lindstrom, 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. agassizi. 



After comparing Professor Martin Duncan's specimen of Sabinotrochns apertus with 

 the series of Dcltocyathus, I conclude that Professor Lindstrdm's conjecture that it is a 



