Klem — The Development of Agaricocrinus. 183 



in nodose or tuberculose extensions with short ridges extend- 

 ing to the sides of the plates, where they meet with the 

 ridges from adjoining plates. Surface granulose. Anal area 

 formed of numerous rows of small plates with a distinct 

 groove at each side. — Geological formation. Burlington, 

 especially Lower Burlington. 



Agaricocrinus Adamsensis, Miller and Gurley. 



Plates thick, part of them subspinous. The first primary 

 radials are sculptured so as to be pyramidal or subspinous. 

 Ventral side moderately convex, covered with large plates and 

 a very large posterior oral which may be formed into a con- 

 ical spine. The anal area is elliptical with no indications of 

 an orifice or only a very small opening on top partly sur- 

 rounded by small plates. — Geological formation. Burlington. 



Agaricocrinus Illinoisensis, Miller and Gurley. 



Ventral disk low, most convex toward the middle. One 

 large convex central oral, otherwise the plates are small and 

 verv little convex. Plates thick, smooth or granular. Anal 

 area not elevated or a tumid swelling, but composed of small 

 Hat plates. — Geological formation. Burlington. 



Agaricocrinus inflatus, Hall. 



Plates of the dorsal cup flat, radials and first interbrachials 

 sometimes a little concave. Ventral disk highly elevated, 

 plates all flat, except the posterior oral which is more or less 

 nodose. Ventral disk strongly inflated at the anal area 

 which is composed of almost flat pieces, with a shallow groove 

 at each side in some. — Geological formation. Burlington. 



Agaricocrinus ornotrema, Hall. 



Plates of the dorsal cup flat. Radial dome plates highly 

 convex. Posterior side of the ventral disk inflated and pro- 

 truding. The middle portion of the inflation consists of an 

 ovoid flattened area, covered by small plates which are sur- 

 rounded by moderately large, strongly nodose or subclavate 

 pieces. — Geological formation. Upper Burlington. 



Aoaricocrinus gracilis, Meek and Worthen. 



First costals, first interbrachials and second anal plates 



