BEVTSION OF PALEOZOIC STELLEROIDEA. 107 



tipped down at the inner side, in an interradius, and not far from the 

 center of the abactinal side of the disk. The surface is probably worn, 

 for it appears perfectly smooth." 



In places the abactinal ossicles are removed, "disclosing the ambu- 

 lacral plates. These plates, which are long and rather thick, seem 

 to be alternate in position. Two of the plates seem to be pierced by 

 pores near their proximate ends, two pores piercing each plate ver- 

 tically. Near the outer end of the more perfect arm there is a space 

 where a few of the small triangular plates are missing, and here also 

 the ambulacral plates can be seen from the upper side. Each plate 

 has a narrow keel on that side. Other details of the plates of the 

 actinal side are unknown." 



Formation and locality. In the Lowville limestone at City View, 

 near Ottawa, Canada, where this interesting asterid was found by 

 Miss A. E. Wilson, in whose collection the holotype now is. 



Remarks. It is interesting to note that this fully developed 

 Promopalseaster, one closely related to P. magniiicus of the highest 

 Ordovicic, occurs in much older rocks; that is, in the Black River 

 formation. This occurrence again brings out the fact often noted 

 by the writer, that Paleozoic asterids are slow to change in characters 

 accessible to the paleontologist. 



P. magniiicus, like P. wilsoni, Raymond states, "has two rows 

 of large marginals and a row of large plates along the top of each 

 arm, while the greater part of the surface is covered with small 

 convex triangular plates. Miller found the plates to be spine-bearing, 

 a point which can not be definitely decided in the present species. 

 From the photograph (submitted by Schuchert) it appears that there 

 are spaces between the small triangular plates on the abactinal sur- 

 face in Pals&aster f magniiicus, while in P. ? wilsoni these plates actually 

 overlap each other." 



PROMOPAL^EASTER PRENUNTIUS, new species. 

 Plate 13, fig. 3; plate 15, fig. 5. 



Remarks. This species is represented by a good specimen showing 

 the actinal side, the other adhering to the limestone. R = somewhat 

 less than 30 mm., r = 7 mm. Width of ray at base about 9 mm. 



P. prenuntius is closely related to P. speciosus, but is distinguished 

 therefrom by the smaller size, less pustulose ornamentation of the 

 plates, and the lower position in the geological column. The plates 

 of the axial area are also more regular in size and there are in the 

 proximal region nearly always two adambulacrals to each inframar- 

 ginal; at about mid-length of the rays the plates of each of the two 

 columns are about equal in number, but every now and then there 

 is some duplication among the adambulacrals. P. prenuntius is 

 equally as spinose as P. speciosus and the former is undoubtedly the 

 ancestor of the latter. 



