. Bulletin - United States National Museum. Science. imperfect, being merely an incomplete disk, and tlie inner ends of tlie rays. It does not conform to the characters of Protaster given in Prof. Forbes's diagnosis, in all respects, since its disk, especially on the upper side, is covered by an integument composed of a vast number of very minute grains of calcareous matter, instead of dis- tinct imbricating scales. It is therefore not improbable that perfect specimens would show other characters that would warrant the establishment of a new genus or subgenus for such forms, in which case the
. Bulletin - United States National Museum. Science. imperfect, being merely an incomplete disk, and tlie inner ends of tlie rays. It does not conform to the characters of Protaster given in Prof. Forbes's diagnosis, in all respects, since its disk, especially on the upper side, is covered by an integument composed of a vast number of very minute grains of calcareous matter, instead of dis- tinct imbricating scales. It is therefore not improbable that perfect specimens would show other characters that would warrant the establishment of a new genus or subgenus for such forms, in which case the name Alepidaster might be applied to the ; GenoTiolotype.—Protaster {?) gr^anuliferus Meek. Original description of Protasterina.—'' Rays five, slender, flexible, and ex- tending much beyond a cir- cular and minutely granu- lar disk, which is provided with short, slender, and outwardly directed spines; inner ray pieces [ambu- lacra] regularly alternating, of an hour-glass shape, and interlocking along the me- dian line, which is there- fore not straight but zig- zag; outer ray pieces elon- gated [adambulacrals or side plates], directed ob- liquely outwards, so as to partly overlap each other; two rows of large pores between the mner [ambulacral] and outer [side plates] ray pieces; in the type-species these pores appear to have been occupied by loosely-fitting subpyramidal plates, some of which have a deep depression in the top, as though they were perforated; their true nature, however, is very uncertain. Oral pieces ten, each pair bemg formed by two of the outer ray pieces. Type, P. ; When the original material of Alepidaster and Protasterina is re- studied, it may be showTi that the latter is not a synonym of the former, but at present the wi'iter does not see any generic differences. Alepidaster is easily distmguished from Protaster, not only by its greater geologic age, but also in that its disk is minutely granular and spiniferous while that
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