298 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



Figs. 6-8. — Urasterella grandis (Meek) (also see plates 28 and 30). 



6. Camera lucida drawing X 8 of part of the abactinal area of a ray proxi. 

 mally. Note how the ossicles are drawn out into nonarticulating blunt 

 spines. 



7. Camera lucida drawing X 4 of the actinal side about the mouth. The 

 complete oral armature is preserved. 



8. Madreporite in outline, X 7. 



From specimens in the Harris collection of the United States National 

 Museum (Cat. No. 40885). 



Plate 28. 



Figs. 1 and 2.— Urasterella grandis (Meek) (also see plates 27 and 30). 



1. Retouched photograph, natural size, of a large and folded specimen. 

 Both ventral and dorsal areas are shown. 



2. Retouched photograph, natural size, of an average individual seen 

 from the actinal side. 



Upper Ordovicic (Richmondian). Near Waj-nesvllle, Ohio. 

 Harris collection of the United States National Museum (Cat. No. 40885). 

 Figs. 3 and 4.— Urasterella pulchella (Billings) (also see plate 30). 



3. Photograph, natural size, of an electrotype, seen from the actinal side. 

 Middle Ordovicic (Trenton). Hull, Ottawa, Canada. 



Original in collection of the Geological Survey of Canada; electrotype in 

 United States National Museum (Cat. No. 60610). 



4. Retouched photograph, natural size, of the abactinal area. 

 Middle Ordovicic (Trenton). Trenton Falls, New York. 



Collection of the Museum of Comparative Zoology, Harvard University 

 (No. 31). 

 Fig. 5. — Urasterella girvanensis, new species. 



Reproduction X 2 of the original figure by Nicholson and Etheridge, 

 somewhat altered. 



From a wax squeeze made by Bather, now in the United States National 

 Museum (Cat. No. 60611). 



Upper Ordovicic. Thraive, Girvan, Scotland. 



Plate 29. 



Fig. 1. — Urasterella ulrichi, new species (also see plate 30). 



Retouched photograph, natural size, of the abactinal side of a cotype. 

 The three short blunt rays are interpreted as healed stumps. 



Middle Ordovicic (Black River). Minneapolis, Minnesota. 



Ulrich collection of the United States National Museum (Cat. No. 60612). 

 Fig. 2. — Urasterella huxkyi (Billings). 



Photograph X 2 of the holotype. Abactinal view. 



Middle Ordovicic (about Chazy). Point Rich, Newfoimdland. 



Collection of the Geological Survey of Canada (No. 554.) 



Plate 30. 



Figs. 1^. — Urasterella grandis (Meek) (also see plates 27 and 28.) 



1-2. Camera lucida drawing X 16 of the adambulacrals with their articu- 

 lar spines and probable paxillse. 



3. Camera lucida drawing X 8 of the two columns of ambulacral 

 plates a little displaced. The podial openings are situated laterally 

 between the thinner ends of the ossicles. 



4. Camera lucida drawing X 7 of the adambulacrals with their spines. 

 From specimens in the Harris collection of the United States National 

 Museum (Cat. No. 40885). 



