Lorraine Faunas of New York and Quebec 327 
other side. The lateral distal quarter of the ambulacral plate 
area is strongly depressed as though for the passage of the tube 
feet. This gives the ambulacral plates on the right side the ap- 
pearance of a short stumpy L, while those on the left side have 
the same appearance with the direction of the foot of the L in- 
verted. This feature is well exhibited along that part of the ray 
traversing the central disc, and along half the length of the free 
part of the ray. Farther out, the ambulacral plates become more 
narrow and the L form is less in evidence. 
Laterally, the ambulacral plates are bordered by the adum- 
bulacral plates. Each ambulacral plate begins at the extremity 
of the base of L-like ambulacral plate and extends beyond the 
base of the next distal plate, successive adambulacral plates over- 
lapping like a series of tiles, concave on the inner side and convex 
outside. A single narrow rotund spine is attached to each adum- 
bulacral plate, the point of attachment being near the distal 
margin of the plate somewhere near its median axis. If any 
other plates are present on the ventral side, these have not been 
detected. Moreover, the presence of actual passages for the tube 
feet has not been seen, though inferred from the visible part of 
the ambulacral plates. 
On the dorsal side, the rays are strongly convex. There are 
two rows of ossicles, the two rows alternating. These ossicles 
are transversely convex, and adjoin laterally a series of distally 
overlapping plates which are assumed to be the adumbulacral 
plates aheady described ; . toward their distal margins each of 
these adumbulacral plates bears a single rotund spine about as 
long as the supporting plate itself. 
The entire dorsal surface of the rays and of the central disc ap- 
pears to have been covered with a thin integument which was 
minutely granular. Some of these granules are larger and may 
have supported minute spines or other appendages. Minute 
spines probably were numerous also on the interambulacral parts 
on the ventral side of the disc, but in the present state of preserva- 
tion of the specimens, the presence of these spines can not be 
determined definitely. 
Only 5 oral ossicles can be detected, one at each interambulacral 
angle; however, since they extend distally like the sides of the 
letter V into the adambulacral rows of plates, it may be assumed 
that they are homologous to the 5 pairs of plates found in typical 
