222 ME. W. PEECT SLADEN ON THE 



wliich radiate from the tips of tlie spinelets and pass to those 

 standing in close proximity around, the bands crossing at various 

 angles, overlying and underlying one other, and forming an 

 interlacing tissue rather than a truly reticulated structure. 

 Spiracula moderately large, irregularly placed, and not numerous. 

 Paxillae with seldom more than three spinelets, which are usually 

 aggregated close together, and especially so along the median 

 line of the ray and at the extremity, forming a crown of small 

 expansion. Towards the disk the spinelets are more widely 

 spaced ; and the paxillae, which form the pseudo-sides of the ray, 

 are disposed in a perfectly straight line, no stragglers encroach- 

 ing on the web or interbrachial area. 



Oscular aperture large and conspicuous ; valves regular and 

 formed of comparatively few spinelets, seldom more than a 

 dozen in each. The outer margin of the oscular ring is very 

 strikingly marked out by short, prominently protruding, pointed 

 spinelets, excentrically directed, very regularly disposed, and 

 from the tips of which the membrane hangs in graceful folds. 



Ambulacral furrows moderately broad, sublanceolate in outline, 

 fairly uniform in width, except near the mouth, where they are 

 constricted, and along the outer fifth, where they taper rapidly 

 up to the extremity. Ambulacral spinelets 2, short, acicular, 

 pointed, covered with membrane forming a moderately developed 

 terminal sacculus. In some specimens this appears to be much 

 more developed in the adoral spine of the pair than in the aboral, 

 which seems frequently to be smaller than the other. The 

 aboral spine is also placed higher in the furrow than the adoral. 

 Aperture-papillae large, and, with their investment, broadly lan- 

 ceolate or acumino-spatulate in form. 



Mouth-plates short and rather broad ; aboral prominence blunt 

 and well-rounded. Each plate with two very short, robust, 

 stumpy secondary surface-spines ; the adoral one (which is placed 

 forward on the plate) shorter even than the mouth-spines proper 

 but much more robust. Mouth- spines proper 4 or 5 on each 

 plate, rather long, fine, and nearly equal in length. 



Actino-lateral spines robust, well-spaced, the 14th or 15tli 

 from the mouth being longest. None meet in the interbrachial 

 median line, not even the longest, the space being filled in with 

 fleshy membrane. 



Colour in alcohol — dirty white in large specimens, greenish 

 grey in those of smaller size. 



