26 
AUG. F. FOERSTE 
the radial accessory plates being confined to the proximal parts 
of the rays. In the more proximal parts of the rays it is im- 
possible to pick out, with any degree of confidence, those plates 
which are to be regarded as belonging to the radial series. The 
nearer accessory plates either equal or exceed the radials in size, 
and the latter either are partially covered or are more or less 
displaced, so that they can not be identified as radials. While 
not in the direct line of descent from Hudsonaster to Palaeaster, 
this species indicates how Palaeaster may have originated by the 
introduction of radial accessory plates and by the displacement 
of the radials, the latter diminishing in size and finally disappear- 
ing altogether distally. 
It is evident that the genus Mesopalaeaster will be broken up 
into various subgenera or genera as the species at present referred 
to this genus become better known. The beginning has been 
made by W. K. Spencer, who founds the new genus Caractacaster 
on the Ordovician species Palaeaster caractaci Gregory, from the 
Caradoc sandstone of Wales and of the Welsh border, character- 
izing this genus by the presence of a continuous series of radials, 
bordered on each side by a column of small radial accessory 
plates which extends the entire length of the rays. For Meso- 
palaeaster schucherti the subgeneric name Hemipalaeaster is pro- 
posed, in view of the partial loss of a distinct series of radials, in 
the proximal parts of the rays. 
Schuchertia magna sp. nov. 
Plate VI, fig, 1 
Measurements. Radius of the disk, from its center to the 
nearest part of the interbrachial arcs, 13 mm. Radius from the 
center of the disk to the tip of the rays, 33 mm.; longer radius 
about 2.5 times the length of the shorter radius. 
Rays separated by large interbrachial arcs, narrowing rapidly 
near the base, so as not to exceed 7 mm. in width at a distance 
of 14 mm. from the tip; narrowing thence more gradually and 
terminating rather bluntly. 
