178 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Reteocrinus stellaris Briures. 
Plate IX. Figs. Sa, b, ¢. 
1859. EE. Brruryes; Geol. Rep. Canada, Decade IV., p. 64, Plate 9, Figs. 4a, 3, ¢. 
1877. S.A. Miter; Catal. Amer. Paleoz. Foss., p. 90. 
1881. W.and Sp. Revision Paleocr., Part IL, p. 193. 
1889. S. A. Mitter; North Amer. Geology and Paleont., p. 277. 
Calyx proportionally larger than in any other species of the genus, 
embracing all the distichals and portions of the palmars. 
Infrabasals and basals unusually large; the former projecting distinctly 
beyond the column, each plate forming a good-sized pentagon. Basals 
heptagonal, slightly truncated and folded inward at the upper ends; four 
of them of equal size, that facing the anal side larger, and the truncation 
wider. The surface of the basals is marked by prominent keel-like pro- 
cesses, meeting in the centre of the plates; one of these proceeds to the 
radials and costals, two others to the infrabasals. At the sides of the pro- 
cesses there are deep depressions, five of them in a radial direction, formed 
by the inflection of the lower angles of the radials and the upper lateral 
margins of the basals; five others, somewhat smaller, triangular in outline 
and interradial, by the basals and infrabasals. The posterior basal, at its 
upper face, has three ridges instead of two, of which the median one is 
continuous with that formed by the anal plates. Radials about one half 
longer than the costals. Costals three; the first and second quadran- 
gular, the third pentangular. Distichals five to seven or more, decreas- 
ing in width upwards, the upper ones taking the form of free arm plates. 
Above the distichals are two more divisions, but only a few of the palmars 
take part in the calyx. The arms are extremely short, and taper rapidly ; 
they are composed of rather long, quadrangular joints. Interbrachial and 
interdistichal areas profoundly depressed, paved by numerous irregularly 
arranged and ill-formed pieces, with a slightly stellate surface. Anal in- 
terradius twice as wide as the others; divided by a longitudinal row of anal 
plates, somewhat narrower than the costals, but resembling them in height 
and curvature. Construction of tegmen, position of anal opening, and 
arrangement of pinnules unknown. Column obscurely pentangular, at the 
upper end composed of very thin, knife-like joints. 
Horizon and Locality. — Trenton limestone; City of Ottawa, Ontario, 
Canada. 
Our figures were made from the type specimens in the Canada Survey 
Museum. 
