ARCTIC SEA TO THE WEST OF GREENLAND. 41 



1853. Solaster endeca, Stimpson, Syn. Mar. Invert. Grand Manan, p. 14. 



1857. Solaster endeca, Liitkcn, Vid. Meddel. N. Forening i Kjobenhavn, 1857, p. 35. 



1861. Solaster endeca, Sars, Ovorsigt af Norges Echinodormer, p. 75. 



1862. Solaster endeca, Dujardin & Hupe, Hist. Nat. Zooph. Echinodennes, p. 354. 



1865. Solaster endeca, Norman, Ann. & Mag. Nat. Hist. ser. 3, vol. xv. p. 122. 



1866. Solaster (Endeca) endeca, Gray, Synop. Spec. Starf. Brit. Mus. p. 5. 



1866. Solaster endeca, Vorrill, Proceed. Boston Soc. Nat. Hist. vol. x. pp. 345, 350. 



1871. Solaster endeca, Hodge, Nat. Hist. Trans. Northumb. & Durham, vol. iv. p. 135. 



1875. Solaster endeca, Porricr, Stellerides du Museum, p. 95 ; Arch. d. Zool. oxp. et gdn. vol. iv. p. 359. 



Rays 8-11 in number, in length equal to, or only a little longer than, the diameter 

 of the disk. The disk is high and considerably arched, the rays being consequently 

 very deep at their base, with sides almost vertical, which gives an appearance of lateral 

 compression ; they taper rapidly towards the tip, however, and become round or sub- 

 cylindrical in shape. In the median interradial line, at the junction of neighbouring 

 rays, there is often a slight depression or furrow, which imparts a very graceful appear- 

 ance .to the Starfish. The abactinal calcareous network is very compact, the interspaces 

 being small and constricted. In large-sized specimens, each of the meshes upon the 

 disk and upper portion of the rays usually contain two (and occasionally three) papulae, 

 but seldom more than one is present in small examples, and towards the extre- 

 mities of the rays. A paxilla or small tuft of spinelets (5 to 10 in number) springs 

 from each intersection, and these form regular parallel lines running obliquely from the 

 margin to the median line of the ray, in consequence of the symmetrical character of 

 the calcareous network and the diagonal arrangement of the ossicles across the ray> 

 10-12 paxillse being counted in such a row at the extreme base of the ray. 



The periproct is central and prominent, and the madreporiform tubercle is situated 

 in an interradium midway between the centre and the arm-angle. There are two rows 

 of ventro-marginal paxillse, those of the upper series, although larger than the general 

 dorsal paxillse, being very much smaller than those of the companion ventral series. 



The paxillse of the lower series are large and compressed in form ; the lateral 

 expansion of the pedicle exceeds the thickness by seven or eight times, and the longer 

 axis is placed at right angles to the median line of the ray. 40-50 of these large 

 paxillae extend between the tip of the ray and the arm-angle ; the series is situate quite 

 over on the ventral surface, and runs with a curve round the margin of the arm-angle, 

 forming a continuous series with those from the neighbouring ray. The paxilla3 which 

 bound the interradial area are very much smaller than those which occur upon the rays 

 proper. 



Each adambulacral plate bears two sets of spines : One a small series, placed very 

 high up in the furrow and running parallel with it, which consists of two or three small 

 spines, the aboral being largest ; the other series forms a fan-like comb of six or seven 

 spines, connected by a membranous web, and is borne upon an elevated keel at right 

 angles to the furrow, almost concealing the small marginal series, which is placed deep 

 within the groove. The spinelets of the transverse series gradually increase in size as 

 they approach the furrow. 



The interbrachial space, which is elongate, narrow, and sagittiform in contour, is 



