MELOCRINID 2. 317 
surrounded by a circular ridge; the arm bases slightly projecting. Surface 
covered by numerous angular ridges, which radiate from centre to centre of 
the plates, producing various geometrical figures. The ridges connecting 
the radials form a pentagon around the basal pit, which is radially disposed 
and of which the sides support five triangles, each one enclosing a smaller ~ 
one. The outer triangles, together with the pentagon, form a five-rayed 
star, and the spaces between the rays of this star are also formed into tri- 
angles, which are followed by other triangles above. 
Basals small, resting completely within the columnar depression. Radials 
and costals of equal height, but the first costal narrower than the second. 
The latter supports at one side an axillary distichal, followed by two small 
palmars and two arms, and at the opposite side by two successive distichals and 
a single arm, making three arms to the ray. Arms stout, biserial, not bifur- 
cating at the lower ends; their upper parts unknown. Arm joints short, 
with parallel faces. First interbrachial large, supporting a smaller, sub- 
quadrangular plate, and three plates in the third row, which in turn are 
followed by five cuneate plates, which extend above the level of the arm 
regions. At the four regular sides, the three middle ones of these plates are 
considerably larger than the outer ones, and touch the orals; at the anal 
side they are followed by a few additional plates, which abut against the 
anal tube. Interdistichals small, consisting of fhree pieces, succeeded by 
two interambulacral plates forming two slits. The number of slits at the 
interradial spaces cannot be ascertained from the specimens. Ventral disk 
slightly tumid; the interambulacral spaces depressed, the plates almost flat, 
the orals and radial dome plates, which are somewhat larger, covered with 
small but sharp nodes. Anus subcentral. Column round, with crenulated 
edges; axillary canal pentangular. 
Horizon and Locality. — Hamilton group ; Alpena, Mich. 
Types in the Museum of the Davenport Academy of Sciences. 
Dolatocrinus glyptus (IHarr). 
Plate XX VI. Figs. 2a, b. 
1862. Cacabocrinus glyptus — Hat; 15th Rep. N. Y. State Cab. Nat. Hist., p. 140. 
1881. Dolatocrinus glyptus — W. and Sr.; Revision Palxoer., Part II., p. 125. 
Syn. Cacabocrinus glyptus, var. intermedius Flatt; 1881, 15th Reg. Rep. N. Y. State Cab. Nat. 
Hist., p. 141. 
Syn. Dolatocrinus ornatus MeeK; 1871, Proceed. Acad. Nat. Sci. Phila., p. 57. 
