46 SMITIISONIAN INSTITUTION 



PLATE XX 

 (All figures natural size except where otherwise stated) 



PAGE 



Figs. 1-3. Lithocrinus divaricatus ( Angelin) 223 



Fig. I. The type: Original of Angelin, pi. 21, fig. 21; 1. post, radial view. Shows plates of anal 

 and regular interradii, and mode of arm division by branching ramules ; stem is 

 25 mm. longer. X f ■ Riks Museum. Wisby (/). 



2a. Type of L. robustus, Angelin, pi. 21, figs. II, 12. Flattened specimen ; from anterior radius 

 (abnormal, with only one IBr). Xf. Riks Museum. Wisby (/). 



2b. Posterior view of same, showing three ranges of solid plates above the anal; 1. post, ray 

 broken. X?- 



Sa. Crushed and broken specimen from Wisby (/) . It is much larger than the type, and has 

 the surface ornament and interbrachial structures well preserved ; shows solid iBr 

 plates isolated by perisome passing into the tegmen. X 2. Riks Museum. 



3b. Same specimen from the side, to show mode of arm branching. X |. 



3r. The ornamentation on a radial. X 3. 



Wenlock Gr. ; Silurian. Gotland, Sweden. 



Figs. 4-8. Forbesiocrinus communis Hall 245 



Fig. 4. One of the types, Pal. Ohio, II, pi. 12, fig. 4. Anterior view of flattened specimen; show- 

 ing the free rays, single iBr plate, and the stem, with expanded proximal part of thin 

 columnals becoming alternating farther down, and longer. New York State Museum, 

 Albany. 



50. Cotype, ibid., fig. 5. Anterior view, showing first iBr plates, and coil of an arm to the end 

 of terminal branch; not much flattened, contour nearly normal. Same collection. 



56. Posterior view of same after additional cleaning. It shows structure of anal side; 

 angular post. B., followed by anal suturally connected with rays, with one series 

 adjoining r. post, ray up to the first IIBr. 



6. Similar specimen, with anal series to the right extending to full height of IIBr, and the 



single iBr. Author's collection. 



7, 8. Two other flattened specimens, showing anal structures and form and proportions of the 



rays. Author's collection. 



Cuyahoga shales; base of Lower Carboniferous. Richfield, Ohio. 

 In none of these specimens is any of the perisome visible, although the spaces that 

 must have been occupied by it above the anal and interbrachial plates are manifest. 



