Corals dredged by H.M.S. e Challenger. 3 563 



from a greater depth than 1600 fathoms. This coral occurs, moreover, 

 on all kinds of bottoms — on Globigerina-m\i& in the Atlantic ; amongst 

 growing branched corals (Madracis asperula) off Bermuda ; on a siliceous 

 bottom, composed almost entirely of diatom-skeletons, in the South 

 Indian Ocean ; and on red clay with manganese nodules in the N". Pacific. 

 It further sustains a range of temperature of 1° C. to 20° C. The 

 specimens from great depths are much larger than those from shallow 

 water, and are very delicate and fragile. Pourtales's largest specimen 

 measured 1 centim. in diameter. We have obtained specimens measuring 

 3 centims. in diameter ; and the specimens from the deep Northern Pacific 

 average 2 centims. in diameter. The specimens from the diatomaceous- 

 mud bottom were, though large, evidently growing under unfavourable 

 conditions as regards the formation of a corallum, the bottom containing 

 only a trace of lime ; hence their coralla were so fragile that they broke 

 at the slightest touch. Prom an examination of the long series of 

 specimens of this coral obtained by us, there seems no doubt of their 

 belonging to one species ; and certain series obtained near Bermuda and 

 the West Indies are undoubtedly identical with F. symmetrica as figured 

 and described by Pourtales. The larger specimens, however, seem to 

 show close affinities with the Lophoserince. Pourtales speaks of the near 

 resemblance of F. symmetrica to Cycloseris hexagonalis. 



Tubipora and Madrepora nasuta, c. f . 

 Dead fragments of these corals were dredged in 200 fathoms oft" Banda. 

 They are instructive as showing how shore forms may be washed down 

 into deep water. 



Notes on a few Corals obtained from a less depth than 50 fathoms. 

 Madracis aspemda. 

 This coral was originally described from Madeira. Pourtales describes 

 it from west of Portugal in 36 fathoms, and from St. Nicholas Channel 

 in Bahia de Cadiz in 120 fathoms. The coral occurs in great quantities 

 on a shoal off Bermuda, known as the South-west Bank, in 30 fathoms. 

 Masses of it came up in the dredge, and a number of specimens on 

 fishing-lines. The coral was also dredged on the shores of St. Vincent, 

 Cape-Verd Islands, and at Fernando de Noronha. 



Flabellum variabile of Semper. 

 In dredging in the Arafura Sea numerous specimens of this species 

 (which, according to Semper, includes F. StoJcesii, F. Oivenii, F. acule- 

 atum, and F. spinosum of M.-Edwards) were obtained. The 'series shows 

 all stages of the multiplication of this coral by fission as described 

 by Semper *. Occurring with F. variabile were found Bhodopsammia 



* Generationswechsel bei Steinkorallen yon C. Semper. Leipzig : W. Engelmann, 



1872. 



