RHODOCRINID^. 231 



Pinnules contiguous ; their joints as long as two of the arm plates. First 

 interradial followed by two rows of interbrachials of two each, except at the 

 anal side, which has from three to four plates in the second row ; the first 

 almost as large as the radials ; the succeeding ones very much smaller. Yen- 

 tral disk slightly elevated, flattened in the middle ; composed of fourteen to 

 sixteen rather large convex or conical plates, indefinitely arranged. Anus 

 marginal, directed obliquely upwards. Column short, gradually tapering ; 

 joints moderately high, the edges almost straight. 



Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa. 



Types in the Museum of Comparative Zoology, Cambridge. 



Remarhs. — The specimen described by Hall as variety divergens is a very 

 mature form of this species. In the smaller specimens the branches of the 

 arms are less divergent. 



Rhodocrinus Barrisi var. striatus W. & Sp. 



Plate XIL Fig. 6, 



Calyx almost cylindrical, broadly truncated at the bottom, but not exca- 

 vated. Plates moderately convex, without nodes. Surface covered with 

 well defined ridges, which meet with similar ridges from adjacent plates. 

 The ridges connecting the basals and those proceeding from the radials to 

 the adjoining basals forming a triangle, which encloses another whose ridges 

 are somewhat less distinct. The form and arrangement of the plates simi- 

 lar to those of the typical form, but the ventral disk proportionally larger, 

 and composed of a greater number of pieces. 



Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa. 



Type in the collection of Wachsmuth and Springer. 



Rhodocrinus truncatus W. & Sp. (nov. spec). 

 Plate XILL Figs. 2a, h, c, d, e, /. 



A rather small species. Calyx wider than high, pentangular in outline, 

 broadly truncated at both ends ; the sides nearly parallel, a little wider at 

 the arm bases. The truncation of the lower end not only extends to the 

 greater part of the basals, but includes small portions of the radials. The 

 base is pentangular in outline, not excavated, except the middle part very 

 slightly for the reception of the column. Plates convex, a little tumid, with 



