28 s. GOTO : 



most is the lougost ; tliis measures 4 mm. on tlie sixth or eighth adambula- 

 cral plate, tlie loDgest spiuelets of tlie fmTOw series exceecling 1 mm. One 

 minut(i thornlet usually sbiucls ou the adorai side of the outer of the two 

 su|jerficial spines ; no other spiuelets are present, and the sm'face of the 

 plate is covered with a membranous tissue. The ambulacral fuiTows are 

 comparatively widely open. Tlie tube-feet are large, and have a rounded, 

 well-developed, knob-like termiuation. 



" The mouth-plates are large, prominent and convex actinally, present- 

 ing a broad and riuinded, but centrally rather flattened, margin towards the 

 actinostome ; and the median sutm'e of the pair is imperfectly closed. Their 

 armatm'e consists of a marginal series of five mouth-spines on each plate, 

 the innermost one being twice or tlu"ee times as long and robust as the 

 others, Avliich are subequal and rather widely sj)aced. On the actinal siu'face 

 of each plate are three (or sometimes only two) robust tapering spiuelets, 

 standing wide apart and forming a line j)arallel to the median sutm-e; these 

 do not appear to attain the size of the superficial actinal spiuelets on the 

 adambulacral x^hitas. The; sm'face of the plates is covered with membrane, 

 and no other spiuelets are present. 



" The actinal iuterradial areas are of very small extent, and do not 

 reach bej'ond the fifth adambulacral plate. The size and number of the 

 intermediate or ventral plates is undeterminable in spirit specimens on ac- 

 count of the membrane with which they are overlaid. So far as can be 

 judged, they appear to be comparatively large, and are certainly few in 

 number. A few of these bear one, or occasionally two, small spiuelets 1.5- 

 2 mm. in length. 



" The anal apertm-e is subcantral but indistinct, smTounded by large 

 spiuelets. 



" The madreporiform body, which is large and oval, is situated midway 

 between the centre of the disk and the odd inter-radial supero-marginal 

 plate. Its surface is slightly convex, finely grooved with numerous highly 

 convoluted striation fm-rows, and has on that account a remarkable resemb- 

 lance to the ' brain ' coral. Several large spiuelets smround its margin, the 

 largest being at its adcentral end. 



