230 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



pyramidal plates." If these extra plates existed, Protasterina will 

 be a good genus, differing not only from Protaster, but also from 

 Alepidaster. 



Apparently no one has actually seen the abactinal side of the rays. 

 The writer also fails to see it in the few specimens studied. It would, 

 therefore, seem that there are no dorsal plates and that the dorsal 

 covering is integumentary or finely granular. 

 This genus contams the follo^ving species: 



A. (?), new species. Trenton. 



A. granuliferus (Meek). Richmondian. 



A. Jlexuosus (Miller and Dyer). Eden and Maysville, 



A. miamiensis (MiUer). Richmondian (Waynes ville) . 



ALEPIDASTER (?), new species. 



In the Walcott collection at Harvard University there are three 

 specimens (Nos. 28, 20, 30) of a "Protaster" that probably wiU prove 

 to be new. They are from the Trenton limestone at Trenton Falls, 

 New York. 



ALEPIDASTER GRANULIFERUS (Meek). 



Text fig. 26. 



Protaster ? granuliferus {Alepidaster at end of description) Meek, Amer. Journ. 

 Sci., ser. 3, vol. 4, 1872, p. 274; Geol. Surv. Ohio, Pal., vol. 1, 1873, p. 68, 

 pi. 3 bis, figs. 8a, 86. — J. F. James, Journ. Cincinnati Soc. Nat. Hist., vol. 18, 

 1896, p. 138.— Parks, Trans. Canadian Inst., vol. 8, 1908, p. 868. 



Original descrijJtion. — "Disk small, apparently circular; rays rather 

 slender, and of unknown length. Dorsal surface of disk and rays 

 covered by an integument composed of innumerable minute grains 

 of calcareous matter. Ventral side of disk not well exposed in the 

 specimen but apparently provided, in the interradial spaces, mtli 

 minute spines directed outward. Oral pieces not well exposed in 

 the specimen. Arm pieces [ambulacrals] regularly alternating, but 

 apparently rectangular at their inner ends, and not interlocking along 

 the minute mesial impressed Hue, longer transversely than in the 

 direction of the length of the rays; each largely excavated at its 

 anterior outer end so as to form a large pore, or porehke depression, 

 and divided transversely by a furrow into two parts, the anterior of 

 which is very short, and the posterior longer, and marked by a minute 

 [muscle] pit at its inner end; about eight or nine of these pieces in 

 each range of each ray included witliin the margin of the disk. Outer 

 arm [or ray] pieces (adambulacral of some) smaller than those of the 

 the inner ranges, and placed edge upward, with an oblique outward 

 direction so as to imbricate outward or toward the extremities of 

 the rays, each bearing one or more minute articulating spines. 



"Breadth of disk, about 0.43 inch; breadth of arms at their inner 

 ends, 0.10 mch." 



