322 PROCEEDINGS OF THE ACADEMY OP [1881. 



longitudinally into ridges, which give to the alternate branches 

 the aspect of fixed arms, which they evidently are. Arm openings 

 large and lateral, with a separate respiratory (?) pore to each 

 opening. 



Interradial, anal and interaxillary plates arranged as in Actino- 

 cri7ius, and scarcely more numerous, they decrease in size upward, 

 the upper ones are very minute. 



Dome convex, in form of a ten-rayed star, indistinctly grooved 

 between the arm bases. Yault constructed of larger and smaller 

 pieces, wliich all decrease outward. The larger ones, wiiich 

 include the apical and all radial plates, are nodose or in part 

 spiniferous ; the smaller ones, including interradial and other 

 accessory pieces are scarcely convex. The inner floor of the 

 vault is strengthened by braces, which increase in thickness as 

 they recede from the centre, and which, on approaching the rim, 

 extend to the calyx, and from tunneled passages, one to each arm 

 opening. 



Column comparatively slender, composed of short, round joints, 

 a part of which, at regular intervals, project out bej^ond the 

 others, and send up and down, all around, at equal distances, five 

 thickened processes or ribs, apparently as a natural provision to 

 give it strength without destroying its flexibility. These pro- 

 cesses give to the column a highly sculptured and somewhat pen- 

 tagonal aspect, especially in its upper portions, where they are 

 prominent and almost continuous vertically. But as these pro- 

 cesses are only attached to the older and larger joints of the 

 column, they gradually grow farther apart as they recede from 

 the body, by the interpolation of the later developed joints, which 

 increase in number downward. Some species, in place of five, 

 have ten or more rows of processes along the column. 



Perforation of medium size ; pentalobate. 



Geological Position, etc. — Teleiocrinus is limited to the Upper 

 Burlington limestone, and is found only in America. 



We place here the following species : — 



*1859. Teleiocrinus aegilops Hall. (Actinocr. aegilops) Supp. Geol. Rep. Iowa, 



p. 5; Meek and Worthen, Strotocr. (B) aegilops, Geol. Rep. 111., r, p. 349. 



Upper Burlington limest. Burlington, Iowa. 

 This is probably a younger stage of Teleiocr. umbrosus. 

 *I861. Teleiocr. althea Hall. (Actinocr. — Calathocr. — althea) Des\ New Sp. 



Grin., p. 1.% Photogr. PI. 4, fig. 13. Upper Burlington limest. Burlington, 



Iowa. 



