REPORT ON CORALS — DEEP-SEA MADREPORARIA. 129 



Introductory Eemarks. 



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." 1 



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 Pourtales. 



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 

 craestion 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 Pourtales' Parasmilia variegata, of which specimens were obtained by 

 the Challenger, under the genus Caryophyllia. I cannot think that the Trochosmilidte 

 have any real affinity with the Astrseidse, or that the occasional presence in them of dis- 

 sepiments within the interseptal chambers is of any classificatory importance. Pourtales 

 has found dissepiments as well developed in some undoubted Caryophyllice. I believe that 



1 Bull. Mus. Conrp. Zool., Harvard, No. 14, 1879, p. 292. 



(ZOOL. CHALL. EXP. — PAET VII. 1880.) G l" 



