Corals dredged by H.M.S. ' Challenger. 3 549 



Dead Fragments drifted from Shallow-shore Regions. 



Tubipora, sp. | ^^ ^ ^^ 20Q &th 



Maclrepora nasuta, c.t. J r 



Zw£ 0/ Corals dredged from less than 50 fathoms, but of especial interest. 

 Madracis asperula (M.-Edw. & H.). — 22nd April, 1873 : south-west 



bank off Bermudas, 30 fathoms ; St. Vincent, Cape-Verd Islands, 



shallow water ; Fernando de Noronha, shallow water. 

 Flabellum variabile ( = F. StoJcesii = F. Oweni = F. aculeatum = F. spi- 



nosum, Semper, ' G-enerationswechsel bei Steinkorallen '). — 12th Sept. 



1874: lat. 8° 56' S., long. 136° 5' E., Arafura Sea, 49 fathoms. 

 "With this species : — Mhodopsammia socialis (Semper), Bhodopsammia 



parallela (Semper), and a genus of Astrcmcece. 

 Heliastrcea cavernosa (M.-Edw. & H.). — 10th Sept., 1873 : off Barra 



Grande, Brazil, 30 fathoms. 

 Fangia symmetrica. — 22nd April, 1873 : south-west bank off Bermudas, 



30 fathoms. 



Notes on the Corals enumerated in the foregoing List. 

 Caryophyllia clavus (Scacchi). 

 Professor Martin Duncan (Ann. and Mag. Nat. Hist. 1870, vol. v. 

 4th ser. p. 289) has remarked on the wide variation displayed by this 

 species, and, after an examination of a long series of specimens, has 

 concluded that C. clavus, C. Smithii, C. cyathus, and C. borealis are to 

 be regarded as varieties of one and the same species, for which the 

 name C. clavus is adopted by him in his final description of the corals 

 dredged by H.M.S. ' Porcupine.' Many varieties of this form have been 

 obtained by the ' Challenger ; ' but the series obtained in each separate 

 locality have been remarkably uniform, showing a similarity of variation 

 produced in the species by the action of certain external conditions. 

 This fact has been found to hold good, not only in the case of Caryo- 

 phyllia clavus but also in that of Dcltocyathus Agassizii and Fungia sym- 

 metrica, as will be subsequently described. As instances may be cited 

 the two following hauls of C. clavus : — On July 10, 1873, in the neigh- 

 bourhood of the Azores, in lat. 37° 24' N., long. 25° 13' W., about thirty 

 specimens of the coral were obtained from 1000 fathoms. Many of them 

 were in the fresh condition with the soft parts uninjured. The corals 

 were all sharply conical, with narrow, pointed, unattached bases, and all 

 uniformly curved. They were from a bottom of fine mud, where only 

 very small particles are present for the attachment of. the young coral. 

 On dredging off the island of Eayal in the Azores in a depth of 50 

 fathoms, another series of C. clavus was obtained. Here the bottom was 

 composed of irregular masses made up of a coarse volcanic sand 

 cemented by Serpula-tubes. The adult Caryophyllias were attached to 



