Stenaster salteri (Billings) 

 Page 52 



1 Specimen exhibiting the abactinal or dorsal view and retaining 



the original integument and the interradial sections of the disk. 



x 3- 



2 Portion of another specimen showing the dorsal side of the 



oral armature and of the base of a ray. x 5. 

 Ordovician : Trenton limestone, Kirkfield, Ontario, Canada. 



Urasterella schucherti nov. 



Page 50 



(See pi. 12, figs. 4 and 5) 



3 Actinal view of portion of oral armature and of base of ray, 



showing the ambulacral groove with the ambulacral plates, and 

 adjoining it the adambulacral plates ; and along the margin the 

 small spiniferous ambital plates, x 5. 



4 Enlargement of portion of abactinal (dorsal) side of ray, to 



show the numerous columns of spiniferous plates, x 5. 

 Devonian : Chemung beds, Kirkwood, Broome county, N. Y. 



Urasterella ruthveni (Forbes) mut. arisaigensis nov. 



Page 46 



(See plate 12, fig. 3) 



5 Specimen (paratype) exhibiting the actinal (ventral) side with 



ambulacral furrow and flanking columns of adambulacrals. 



* 5- 



6 Specimen (paratype) presenting the abactinal (dorsal) view. 



The outlines of the columns of plates are seen in the distal part 

 of the left upper ray; the remaining surface shows only the 

 bases of the rods projecting from the plates. From gutta- 

 percha squeeze, x 4. 



Silurian : Arisaig series at mouth of Stonehouse brook, Nova 

 Scotia. 



The originals of all figures are in the New York State Museum. 



170 



