146 



'rransactiotu 



The median radial plates are somewhat larger than the laterals, which 

 extend to the tip of the ray. The madreporite is single, small, about 

 half the diameter of any of the other plates of the disc, and situated close 

 to the centre. 



Marginals well developed. The supra-marginals are large, flat, squarish, 

 lying on the upper surface. There are 7 on each side, excluding the ter- 

 minal. In one specimen some few of the supra-marginals bear 1 to 3 quite 

 small blunt spines on the outer edge. In the other specimen they are little 

 evident. 



In each interradius a couple of plates, with adjacent sides straight^ 

 extend from the primary interradial to the marginals. 



At each side of the base of the arm is a small valvate pediceliaria,. 

 though not quite regularly disposed, as it may be absent from one side. 

 They are usually carried on one of the small supplementary plates, between 

 the supra-marginal and laterals. In one case there is a pedicellaria on 

 a special plate close to the median row. 



On the actinal face the interbrachial areas are formed of small plates 

 similar to those of the upper surface. There are no pedicellariae or papulae 

 on this surface. 



The infra-marginals are similar in form and number to the supra- 

 marginals. Each bears a horizontal row of 3 or 4 short conical spines. ( om- 



pressed from above down- 

 wards, closely set along the 

 outer edge of the plate. 

 In each group the 2 middle 

 spines are rather longer 

 than the 2 outer ones. 

 There is a gap between the 

 groups, so that the saw- 

 like fringe is interrupted. 



The adambulacral arma- 

 ture : The series of furrow- 

 spines and the series of 

 actinal spines are united 

 together to form a sort of 

 membrane, so that the 

 groove is margined by 

 2 membranes on each 

 side. The furrow-spines 

 are 2 to each plate, cylin- 

 drical ; the actinal spines are solitary over the greater length of the 

 groove, but duplicated on the plates near the mouth, flattened and broad, 

 with very blunt points. There are no special teeth at the oral angles. 



Colour. — Mr. Oliver gives the colour as " bright red." When dried they 

 are pale bufi^, with indications of a richer brown near the apex. 



Locality. — Meyer Island : Under stones in rock-pools (10/5/1908) ; and 

 one was dredged " on coral, 3 fathoms " (1/3/1908). 

 Dist.rihiifum. — The genus is Pacific and Indian. 



Remarks. — Tlie juvenile form of fi. carinijera v. Martens, figured by Sladen 

 (" Challenger " Report, pi. 52, figs. 5-8), differs from the present species in 

 the relatively greater size of the plates, in the presence of large spines on 

 the infra-marginals, and none, or very smull ones, on the supra-marginals ; 



W 



Fig. 4. 



Fig. 5. 



Gytnnasteria lissotergu in. 

 Fig. 4. The abactinal surface of the disc and of one 



ray (x 3). 

 Fig. 5. The actinal surface of one ray (x 3). Details 



are inserted on one side onlv. 



