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



is suiTounded by a bundle of diacts, which are provided with prougs ou their pointed 

 extremities (PI. V. fig. 6), and have four conical swellings on the axial intersection. 



The floricomes of the outer skin exhibit a form quite similar to that in Euplectella 

 aspeiyillum, but it is important to note that they are almost twice as large. I usually 

 found seven terminal rays on each principal. 



The gastral skeleton exhibits on the inner side of the quadrate ledge-like network 

 which projects into the large lumen of the tube the same slender pentacts which occur 

 in similar positions in Euplectella aspergillum ; on the other hand, on the inner side 

 of the diverticula-like chambers which underlie the external gentle archings, slender 

 dagger- like hexacts occur, wdth a prolonged distal ray, and a proximal ray projecting 

 radially into the inner lumen (PI. VI. fig. 3), raising the gastral membrane into pointed 

 tubercles, and bearing on its end a floricome just like the similar dermal hexacts. It is 

 interesting, however, that this gastral floricome does not agree either in size or form with 

 the above-mentioned dermal floricome. The number of the terminal rays belonging to 

 each principal amounts to ten or twelve in the former, but only to seven in the latter. 

 The cup formed by these terminal rays is relatively broader (the diameter of the whole 

 floricome is only half as large as in the case of the dermal floricome) (PL V. fig. 4). 



Fragments of Euplectella suherea, Wyville Thomson, were collected by the Challenger 

 in three different places : — 



(1) In 600 fathoms, lat. 36° 25' N., long. 8° 12' W.; Station IV.; west of Gibraltar. 



(2) In 1090 fathoms, lat. 35° 47' N., long. 8° 23' W.; Station V.; w^est of Gibraltar. 



(3) In 1600 fathoms, lat. 10° 11' S., long. 35° 22' W. ; Station 124; between 

 Pernambuco and Bahia. 



The figure (PL V. fig. 1) is reconstructed from somewhat defective, and yet in some 

 respects adequately preserved, specimens found to the west of Gibraltar (Stations IV., V.). 



In a short review of the results of the French " Travailleur " expedition, Milne- 

 Edwards^ has noted (1881) that "two fine specimens of Euplectella suherea were taken 

 off the Berlingues at 3307 metres." And Filhol" adds, " Les Euplectella suberea sont 

 largement repandues dans I'Atlantique nord. Pendant la croisiere du Talisman nous les 

 avons draguees a diverses reprises par des fonds variants entre 900 et 2300 metres. En cer- 

 tains points elles etaient d'une extreme abondance etdevaient couvrir d'assez vastes capaces." 



3. Euplectella cucumer, R. Owen. 



Since I had the opportunity of seeing the original specimen of Euplectella cucumer, 

 Owen, which is preserved in the British Museum, and of examining it so far as was 

 possible without injuring the beautiful specimen, I shall here take the opportunity of 

 briefly expressing my opinion in regard to this interesting form. 



' Comptes rendus, xciii. pp. 871-931 ; Ann. and Mag. Xat. Hist., ser. 5, vol. ix. p. 46. 

 ^ La vie au fond des mers, p. 282, pi. iii. 



