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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



[vol. 47 



Comparisons. — As the various forms of Pseudocrinites are easily 

 recognized on account of their constant characters, the writer does 

 not hesitate to describe this broken specimen as a new species. Its 

 greatly elongate, narrow form distinguishes it from all the others. 

 P. clongatiis is closely related to P. sub quadratics, as both have the 

 same general form, size of ambulacral plates, and sculpture, but the 

 former is readily separated by being more elongate with the sides of 

 the theca straighter, and more especially by the far greater size, being 

 2^2 times larger than P. sitbquadrattts. 



Formation and locality. — The holotype was found by Air. Perdew 

 in the Manlius formation on Martin's mountain, near Lodger Per- 

 dew 's farm in Pleasant valley, Bedford county, Pennsylvania. 



Cat. number 35,065, U. S. X. M. 



PSEUDOCRINITES PERDEWI Schuchert 



(Plate XXXVI, figures 1-3; Plate XXXIX, figures 8-10) 

 Pseudocrinites perdewi Schuchert, Amer. Geol., xxxn, 1903, p. 238. 

 The four following specimens represent four stages in the growth 

 of this species : 



Length | Width 



Depth Brachioles (total) Rhomb 1-5 Rhomb 12-18 Rhomb 14-15 



Specimen i 16 mm 1 1 mm 

 Specimen 2 24 " 17 



9 mm 



Specimen 3 

 Specimen 4 



27 

 39 



15 



?20 



23 



48 

 76 

 90 



\ 20 dichop. 

 42 " 



53 " 

 82 " 



34 dichop. 

 48 " 

 65 << 

 114 " 



40 dichop. 

 58 « 

 82 " 



General form pear-shaped, with the sides appressed. 



of the individual 

 CV) 



/T/6B 



For shape 

 plates and 

 their ornamentation, see the 

 diagram and plate-figures. 



Ambulacra wide, very prom- 

 inent, with vertical angulated 

 sides and flat or slightly 

 trough-shaped oral surfaces. 

 In specimen number i, the 2 

 ambulacra taper rapidly and 

 extend along the periphery of 

 the theca for one-third its 

 length. In number 2, they are 

 just one-half the length of the theca, in number 3 nearly two-thirds 

 the length, while in number 4 they are about one-half the length. 

 This shows that the length of mature ambulacra is somewhat vari- 





32. — Analysis of Pseudocrinites 

 perdewi Schuchert. 



