446 
Aug. F. Foerste 
84. Agelacrinus holbrooki, James 
( Plate I, Figs. 1 A-F ; Plate IV, Fig. 1) 
{Paleontologist, No. 1, p. 2, 1878, 
Journal, Cincinnati Society of Natural History, vol. X, p. 25, Figs. A, B, 1887) 
A specimen of Agelacrinus holbrooki, from the James collection, 
is in the Walker Museum at Chicago University, and is numbered 
1004. I strongly suspect that this specimen is the type, for the 
following reasons. The left anterior ray is preserved almost 
entire. The proximal part of the left posterior ray for a distance 
of about 12 mm. from the probable center of the oral parts is 
missing. Of the right posterior ray only the terminal U-shaped 
part is present; the remainder, from the oral parts to that part 
which is about as far distant as the more remote part of the anal 
opening, is missing. There is no trace of the right anterior ray, 
of the interambulacral areas above or below this ray, or of the 
oral parts. Only the distal, U-shaped part of the anterior ray is 
present, but the proximal part of the left anterior interambulacral 
area seems sufficiently preserved to indicate with some exactness 
the direction of the proximal part of the anterior ray. If, without 
giving any attention to the orientation of the rays, the specimen 
be turned so as to place at the top the exposed part of the fragment 
of x^edicel valve of Rafinesquina alternata, upon which the specimen 
rests, then an outline similar to that of the published figure of the 
type is presented; that part of the margin of the theca which is at 
the top curves outward in a concave manner, and that part which 
is at the bottom curves downward and inward, so as not to be 
exposed. In that position, however, the orientation of the rays 
is different from that presented in the published figure of the type. 
I strongly suspect that the artist took considerable liberties with 
the specimen, first drawing the general outlines and general form 
of the specimen correctly, and then twisting the specimen through 
an angle of about 60 degrees to the right before putting in the 
details of the rays and interambulacral areas. 
One of the most characteristic features of Agelacrinus holbrooki 
is the strong convexity of the upper surface of the theca. The 
greatest diameter of the specimen is 30 mm., and this is the diame- 
ter also in a transverse direction. The height is about 16 mm., the 
theca rising rather abruptly from the margin, thus giving it the 
sub-globose surface noted by James. Ambulacral rays rising but 
