BATOCRINIDZA. 525 
rather large, decreasing gradually in size ; disposed generally in six rows, of 
which the upper ones are irregular and not readily recognized; the first plate, 
which has the size of the first costals, supports two plates in the second row, 
and three in the succeeding ones. Anal interradius wide, the first anal plate 
as large as the radials; succeeded by three plates, the middle one the smallest, 
and four or five plates in the rows above. Tegmen almost flat, its diameter 
remarkably small, owing to the constriction at the upper regions of the dorsal 
cup. In the casts there are no traces of disk ambulacra, and nothing to 
indicate the presence of orals in this species; the whole surface is covered 
by the impressions of small, irregular plates, surrounded by what appears to 
represent the arm openings, which were apparently arranged in groups, 
forming a circle around the disk. ‘The exact number of primary arms could 
not be ascertained from the specimens, but we have reason to believe there 
were eight arms to the ray. Anus subcentral, apparently not large. 
Horizon and Locality. — Upper part of Niagara group, near Chicago, Ills. 
Periechocrinus infelix (Wincu. and Marcy). | 
Plate L. Figs. 2a, b, ¢, d. 
1865. Megistocrinus infelic — WincuEtt and Marcy; Mem. Bost. Soc. Nat. Hist., p. 110, Plate 2, Fig. 7. 
1879. Syn. of Saccocrinus Christyti — Watt; 28th Rep. N. Y. State Mus. Nat. Hist., p. 127. . 
1881. Saccocrinus infelix —S. A. Minter; Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 260, Plate 6, | 
Figs. 2, 2a, 6. 
1885. Pertechocrinus infelix (?) — W. and Sp.; Revision Paleocr., Part III., p. 106. 
Syn. Saccocrinus Egani —S, A. Mitter; Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 178, Plate 4, | 
Figs. 4, 4a. 
Smaller than the two preceding species. Dorsal cup somewhat obconical, 
higher than wide; sides convex, abruptly spreading from the basals to the 
top of the radials; the upper regions almost cylindrical, sometimes a little 
spreading; surface of plates slightly convex, and covered with obscure 1 
radiations. | 
Basals small, forming a shallow pentangular cup. MRadials and costals 
rising to three fourths the height of the calyx; the radials much wider than 
the first costals, about as wide as long, and the sloping upper faces almost as 
short as the upper face; the first costals, as a rule, a little larger than the 
a 
second. Distichals two, one third smaller than the preceding axillary. Pal- 
mars two, small. Interbrachial and interdistichal areas somewhat grooved at 
the upper ends. Interdistichals disposed in six to seven rows; the first as 
large as the first costals, with obtuse upper angle and long lateral faces, great- 
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