Paleontology of the Cincinnati Group. 



Genus 4.— PTYCHOCRINUS Wachs. & Spring., 1885. 



In general form resembles Glyptocrinus ; radials with a 

 fold-like strong, tubular ridge along their median line ; inter- 

 radial spaces depressed ; under-basals 5 ; basals 5, large, all 

 hexagonal; primary radials 3X5; nrst ones heptagonal, but 

 upper-sloping sides, facing the azygous side, longer, forming 

 a deep notch for a very large anal plate ; secondary radials 3 

 or more, having the appearance of arm-plates, and gradually 

 passing into free joints; strong arm-like pinnules given off 

 from alternate sides; interradials consisting of 1 plate in the 

 first row, 2 in the second, and 3 in the third; azygous side 

 wider; first plate extending far down between the first 

 radials, sometimes touching the basals, and 3 plates instead 

 of 2 plates in the second series; column small, cylindrical. 

 (Review of Palaeocrinoidea, Part III. [in Proc. Acad. Nat. Sci. 

 Phil, for 1885], p. 100.) 



Remarks. — This genus was formed by Messrs. Wachsmuth 

 and Springer for the reception of 3 species, two of which had 

 been referred by Miller to his Gaurocrinus. Two of these 

 occur in our own region, and are given below: 



1. — P. ANGULARis Miller & Dyer, 1878. 



Body angular, due to the depression of interradial spaces, 

 and the downward extension of the basals below junction of 

 the column ; radial pieces marked by a strong ridge, orna- 

 menting the surface; under-basals 5, small, pentagonal, wider 

 than high; basals 5, hexagonal, two lower faces resting be- 

 tween under-basals, and two upper-sloping sides supporting 

 the first radials ; each basal with an angular or wedge-shaped 

 tubercle ; first radials larger than the basals, heptagonal, 

 wider than long; second and third radials smaller and hex- 

 agonal; first secondary radial hexagonal, longer than wide ; 

 second, heptagonal, supporting on each of the upper sides a 

 series of brachial pieces; interradial spaces have an hexago- 

 nal plate between the upper sloping sides of the first radials, 

 followed by 2 plates on its upper sides, and these by 3 plates 

 in a row between the lower part of the first secondary radials, 



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