EEVISION OF PALEOZOIC STELLEROIDEA. 291 



Plate 7. 



Figs. 1-4. — Palseaster niagarensis Hall. 



1. Camera lucida drawing X 4 of the abactinal side in its present 

 preservation. HolotjToe. 



2. Abactinal side of theholotype restored, X 4. The drawing probably 

 has too many accessory disk pieces. 



3. Camera lucida drawing X 4 of the actinal side of one of the rays of 

 the holotype. Since this drawing was made the rock in the ambulacral 

 furrow has been dug away down to the ambulacral plates, which are 

 small and deep-seated. 



4. A few of the inframarginals and supramarginals from the abactinal 

 side to show the smooth central areas surrounded by granular borders, X 4. 



Siluric (Rochester shale). Lockport, New York. 



Collection of Cornell University (No. 7331). 

 Fig. 5. — Mcsopalxaster find (Ulrich) (also see plate 9). 



Camera lucida drawing X 16 of one of the rays. The ossicles are always 

 more or less displaced in this species. 



Upper Ordovicic (Eden shales). Cincinnati, Oliio. 



Ulrich collection of the United States National Museum (Cat. No. 60604). 



Plate 8. 



Figs. 1 and 2. — Mesopalseaster shafferi (Hall). 



1. Camera lucida drawing X 8 of the abactinal side of a one-third 

 adult-sized specimen. As the medial disk pieces are displaced in the 

 individual, they are here drawn in in their probable natural arrangement 

 all should be pointed like the central disk plate. 



Upper Ordovicic (Maysvillian, Corryville member). Cincinnati, Ohio. 

 Vaupel collection of the United States National Museum (Cat. No. 

 60G05). 



2. Camera lucida drawing X 3 of the actinal area of a mature indi- 

 vidual. 



Upper Ordovicic (Richmondian). Waynesville, Ohio. 

 Harris collection of the United States National Museum (Cat. No. 

 59391). 

 Fig. 3. — Miomaster drevermanni Schondorf. 



Actinal side as reconstructed by Schondorf. Natural size. 

 Lower Devonic (Upper Coblenzian). Miellen, Germany. 



Plate 9. 



Fig. 1. — Mesopalaeastei' (?) parviusculus (Billings). 



Camera lucida drawing X 5 of a gutta-percha squeeze of the holotype, 

 actinal side. 



Siluric (Lower jVrisaig). Arisaig, Nova Scotia. 



Original at McGill University; gutta-percha squeeze in United States 

 National Museum (Cat. No. 60620). 

 Fig. 2. — Mesopalxaster (?) cataractensis, new species. 



Photograph X 3 of the well-preserved holotype. 



Siluric (Cataract formation). Hamilton, Ontario. 



Collection of the Hamilton Natural History Society. 

 Fig. 'i.—Mesopalxastcr (?) granti (Spencer). 



Photograph X 2 of a specimen showing the dorsal side. 



Siluric (Cataract formation). Hamilton, Ontario. 



Collection of Peabody Museum, Yale University. 



