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MR. W. PERCY SLADEW OK THE 



aborted or indistinguishable from tbe squamules of tbe plate. 

 Wlien the side or lateral wall of the ray is placed in direct view, 

 the above-mentioned spines of the inferior plates are all visible, 

 and they, together with the spinelets of the superior plates, appear 

 to form a continuous vertical series. The marginal spine is very 

 little, if at all, longer than the outer spine on the supero-mar- 

 ginal plate, and all these spines stand at an angle to the super- 

 ficies of the plate and are directed upward and outward. Very 

 short, widely spaced, papilliform squamules are distributed over 

 the whole of the infero -marginal plates, and tlie granulation of 

 the supero-marginal series partakes of the same character and is 

 indistinguishable at the junction of the plates. 



The ambulacral spines are short and robust, subpapilliform, 

 and do not taper, and tliey stand more or less perpendicular to 

 the surface of the plate. The inner series are 4 or 5 in number, 

 and their base-line forms a sliglit angle projecting into the furrow; 

 thie middle spinelets are a shade larger and more robust than the 

 others. The ambulacral spinelets that occupy the rest of the 

 plate behind the furrow-series are little more than elongate 

 papillae ; they are small, stumpy, covered with membrane, and 

 are rather widely spaced, no definite order of arrangement being 

 discernible, although about two irregular rows may be traced 

 in some instances. The spinelets on the ventral plates are 

 similar in character and disposition to the foregoing, and they 

 merge imperceptibly into the squamules of the infero-marginal 

 plates. This uniformity in the dermal appendages imparts a 

 characteristic appearance to the ventral aspect of the starfish. 



Mouth-plates elongate, each with two short, flattened, truncate 

 spinelets at the inner extremity, then about six pairs of spinelets, 

 short and robust, standing perpendicular on the surface of the 

 plate and forming two series apposed to one another ; and then 

 about four rather broader, shorter, and more robust spinelets, 

 forming a single seines in continuation as it were of the two 

 apposed series, at the outer extremity of the plate, towards 

 which the spinelets decrease as they proceed outward. Conse- 

 quent on this method of arrangement there is a marked division 

 of the mouth-plate armature into two narrow series along the 

 median line of each mouth-angle. 



The paxillse of the dorsal area are small and compact, and 

 composed of six to nine sj)inelets, of which one is central. The 

 spinelets are short and robust^ and are directed upward, their 



