612 THE VOYAGE OF H.M.S. CHALLENGER 



the furrow, over which it is directed horizontally and riot quite at a right angle to the 

 axis of the plate, but directed very slightly aborally. Its length is about equal to half 

 the width of the furrow, and it is covered with a membrane so delicate and close fitting 

 as to appear naked. Not more than one or two pedicellarise are present, and these are 

 often wanting. The actinal spine is articulated on a small tubercular eminence near the 

 middle of the actinal surface of the plate ; it is about 1'5 to 2 mm. in length at 20 mm. 

 from the base of the ray, delicate, cylindrical, rather robust at its base and tapering to a 

 sharp point, and is invested with a delicate membranous sheath crowded with minute 

 pedicellarise. The lateral spines are delicate, cylindrical, tapering, 3"5 to 4 - mm. in 

 length at 25 mm. from the base of the ray, and encased in a membranous sheath crowded 

 with pedicellarise, and each is articulated on a small, triangular, rudimentary plate — ■ 

 the representative of an infero-marginal plate. These small rudimentary plates are 

 sutured to the adambulacral plates by the base of the triangle, and the lateral spine is then 

 articulated on the aboral facet, the normal direction of the spine being consequently out- 

 ward at an angle of about 45° to the axis of the ray, and this conspicuous little plate 

 recalls in the most vivid manner the attachment of the pinnule of a Comatula. At the 

 extreme base of the ray there are two of the rudimentary marginal plates (which Sars 1 

 named dorso-marginal) ; the first, which articulates on the so-called odontophore, is as long 

 as the adambulacral plate on which it is superposed, whilst the next is very much smaller. 

 I consider that these are the representatives of infero-marginal plates and not supero- 

 marginal, as supposed by Sars — a mistake which I would suggest has arisen from the 

 adambulacral plate appearing at first sight to stand as an inferior marginal plate in rela- 

 tion to these small plates. From the fact that the plates in question are attached to 

 the adambulacral plates and the odontophore, and likewise when further out on the 

 ray bear the lateral spine, it would, in my opinion, seem far more natural to rank 

 them as the rudiments or representatives of infero-marginal plates than of supero- 

 marginals. 



Colour in alcohol, a rather dark brownish grey, the ambulacral tube-feet being dark 

 brown. 



Locality. — Station 146. Between Marion Island and the Crozet Islands. December 

 29, 1873. Lat. 46° 46' 0" S., long. 45° 31' 0" E. Depth 1375 fathoms. Globigerina 

 ooze. Bottom temperature 35°'6 Fahr. ; surface temperature 43° - Fahr. 



Station 147. West of the Crozet Islands. December 30, 1873. Lat, 46° 16' 0" S., 

 long. 48° 27' 0" E. Depth 1600 fathoms. Diatom ooze. Bottom temperature 34°'2 Fahr. ; 

 surface temperature 41 o- Fahr. 



Remarks. — Brisinga rnembranacea is remarkable for the extremely delicate and rudi- 

 mentary character of the abactinal skeleton which is represented only by transverse bars 



1 On some remarkable forms of animal life from the great depths off the Norwegian coast, Part II., 

 University Program, Cbristiania, 1875, p. 9. 



