30 FOSSIL ASTEROIDEA. 



Remarks. — It will be at once seen on referring to the figures that Woodward's 

 Pentagunaster lunatns, which is drawn on PI. IV, fig. 1 a, of this Monograph, is a 

 distinct species. The rays are more jDroduced, and are narrower at the base. The 

 infero-marginal plates are twice as numerous, the marginal border is less broad, 

 and the plates are much shorter in proportion to their breadth. Their punctation 

 is also different. The actinal intermediate plates are smaller in relation to the size 

 of the actinal interradial areas, and their punctation is different from that which 

 characterises Pentagonaster megalojdax. The armature of the adambulacral plates 

 also appears to be more regular in its arrangement. 



Under these circumstances I have no hesitation in considering the form under 

 description a distinct species. 1 much regret having to impose a new name, as 

 this form has for a long time been known under the specific name of lunatus ; 

 the course, however, seems unavoidable, as the actual type of the real Pentago- 

 naster lunatus described by "Woodward is in existence, and there can, in my 

 opinion, be no question as to its being a diff"erent species. 



Since the preceding sheet was printed off I have found several specimens in 

 the British Museum which show the abactinal aspect of the disk. I have little 

 hesitation in referring these examples to Pentagonaster megaloplax, and a drawing 

 of one of them is given on PL XIII, fig. 1 a. The infero-marginal plates all show 

 more or less distinctly the characteristic " scrobiculate " or areolated pits already 

 described. A similar ornamentation also extends upon the supero-marginal 

 plates, but is confined to the lateral wall which falls in the margin of the disk. 

 The curvature which unites the abactinal and lateral areas of the plate is more or 

 less abrupt, and the lateral wall of the disk is consequently vertical and not 

 rounded, as a rule. The abactinal area of the supero-marginal plates is covered 

 with small, uniform, granular eminences (see PL XIII, fig. 1 h). Two or three 

 supero-marginal plates at the extremity of the ray meet the corresponding plates 

 of the opposite side of the ray in the median radial line, and a rapid diminution 

 in breadth occurs as they approach the extremity. 



Ge?i«s— METOPASTBR, Sladen. 



[MiTwirof = a cheek-piece.] 



Body depressed and pentagonal or stellato-pentagonal in contour, the rays 

 being produced to a very slight degi'ee. Marginal plates covered with well- 

 spaced uniform punctations, upon which granules were originally borne, and 

 surrounded by a narrow depressed border with very minute and crowded puncta- 



