50 SMITHSONIAN INSTITUTION 



Holotype. — The calyx herein described is in the author's collection. 



Horizon and locality. — Keyser division of Helderbergian, Schoharie, New 

 York; Keyser, West Virginia. Possibly also the Linden formation in Benton 

 County, Tennessee. 



5. Scyphocrinus pratteni (McChesney) 

 Plates VII, figs, la, b; VIII, figs. 1, 2a, b 



i860. Forbesiocrinus pratteni McChesney ; Trans. Chicago Acad. Sci., Extract No. 1, p. 29. 



1865. Forbesiocrinus pratteni McChesney ; plates illustrating in part new species fossils, 



pl- 5. ng- 4- 



1866. Melocrinus pratteni (McChesney) ; Shumard, Trans. Acad. Sci. St. Louis, vol. 2. 



P- 381. 

 1868. Melocrinus pratteni (McChesney) ; McChesney, Trans. Chicago Acad. Sci., vol. 1, 



p. 22, pl. 5, fig. 4. 

 1881. Melocrinus pratteni (McChesney) ; Wach. and Spr., Proc. Acad. N. S. Phil., 296 

 (Rev. Pal., vol. 2, p. 122). 



( ?) Syn. Camarocrinus saffordi Hall, 1879, 28th Rep. N. Y. St. Cab. 

 Nat. Hist., 208; pl. 36, figs. 1-6; pl. 37, figs. 1, 2; Schuchert, 1904, Smith- 

 son. Misc. Coll., vol. 47, pt. 2, p. 270, pl. 40, fig. 10. 



Calyx extremely large, massive, lageniform; broadly conical from base 

 to widest part about the zone of axillary primibrach, thence contracting and 

 becoming cylindrical toward the arm-bases. Height about equal to maximum 

 width. Interbrachial areas at widest part strongly protuberant, with primi- 

 brachs and first secundibrachs deeply depressed between them ; higher up this 

 condition is reversed, the secundibrachs being elevated into a broad median 

 ridge, while the interbrachial pavement (fixed pinnules) is low, rather flat, 

 with obscure sculpturing. Secundibrachs about 12, the first being elongate, 

 followed by gradual diminution in length until the upper ones are less than 

 one-eighth as long as wide; median ridge begins at about the fifth plate, passing 

 into a broadly rounded trunk toward the arms. Fixed pinnules strongly modi- 

 fied by surface sculpture, and not readily distinguishable. Primary inter- 

 brachials large, in about five or six ranges of 1,2, 3, 3, 2, 1, with one or more 

 additional plates in the posterior interradius for the ranges above the second. 

 Plates in lower part thick, convex, smooth, with obscure connecting ridges, 

 often pustulose or obtusely spiniferous; in the upper interbrachial region flat 

 and without sculpturing. Arms and stem not preserved, except for a few of 

 the proximal columnals, which are extremely thin. 



Dimensions of a maximum specimen : Height of calyx to axillary secundi- 

 brach, 90 mm. ; width at widest part about 100 mm., reduced above to about 

 75 mm.; diameter of column proximal to calyx, 12 mm. Diameter of asso- 

 ciated root bulbs, 150 mm. 



This species is the most striking example of the group to which it belongs, 

 and is so completely distinct in facies from those of the elegans group as not 



