REPORT ON CORALS—DEEP-SEA MADREPORARIA. 129 
Iyrropuctory REMARKS. 
The number of Corals dredged by H.M.S. Challenger in deep water was comparatively 
few, having regard to the very large number of stations (354) at which dredging operations 
were conducted. No doubt this result was largely due to the fact that during all but the 
earlier portion of the voyage, a trawl-net with a somewhat wide mesh was made use of 
instead of a dredge, as yielding the best general results. The trawl made use of was an 
ordinary fisherman’s trawl-net, with none of the improvements which Mr Alexander 
Agassiz has since introduced and employed with such great success in his dredgings from 
the United States’ Coast Survey steamer ‘ Blake.”? 
Of a great many species only a single specimen or two or three were obtained 
by the Challenger, but specimens of very many of these rare forms, most of which 
were hitherto unknown, have been since dredged by Mr Agassiz, as I am informed 
in a letter recently received from Count Pourtalés. 
I have found considerable difficulty in assigning many of the forms obtained to 
species new or old. The specimens dredged were always dead when they reached the 
surface, and the soft parts were often more or less decomposed or battered, having suffered 
during the long period consumed in raising them to the surface. With the structure of 
the corallum only to judge by, it is very often extremely difficult, often impossible, to 
determine the exact affinities and relations of many forms, and in not a few instances the 
question at issue not only refers to the nature of the genus to which certain corals shall 
be referred, but even to which family a specimen shall be relegated. No naturalist who 
has worked at the determination of the species of corals has doubted that the classification 
of MM. Milne-Edwards and Haime is faulty in very many respects, and needs thorough 
revision. Such revision will only be possible when the anatomy of the soft parts of very 
many forms has been carefully worked out. Unfortunately, there are no other animals in 
which the technical difficulties in the investigation of the anatomy are so difficult, or in 
which they require so long a time for their accomplishment as in the Madreporaria. I have 
been able to make very few investigations of this nature, though I hope to work at the 
subject at leisure at some future time. The results of a few observations which I have 
made in the case of two or three species are given in the present memoir in connection 
with the descriptions of the species to which they apply. 
I have placed Pourtalés’ Parasmilia variegata, of which specimens were obtained by 
the Challenger, under the genus Caryophyllia. I cannot think that the Trochosmilidee 
have any real affinity with the Astreeidee, or that the occasional presence in them of dis- 
sepiments within the interseptal chambers is of any classificatory importance. Pourtalés 
has found dissepiments as well developed in some undoubted Caryophylliv. 1 believe that 
1 Bull. Mus. Comp. Zool., Harvard, No. 14, 1879, p. 292. 
(ZOOL, CHALL., EXP.—PART vil.—1880.) G17 
