180 PROCEEDINGS OP THE ACADEMY OP [1886. 



species the place of union is still indicated by a depression. Such 

 is the case also in Dolatocrinus and Stereocrinus. In Agassizo- 

 crinus an anchylosis takes place between the iinderbasals, all 

 suture lines disappear in the older specimens. In Eupachycrinus 

 ornatus and EupachycyHnus gemmiformis, which occur in the 

 same bed with Stemmatocrinus cernuus, the sutures are fre- 

 quently not visible, and the plates apparently constitute a solid 

 disk which in form and proportions resembles that of Stemmato- 

 crinus. 



STEMMATOCRINUS TRAUTSCHOLDI ' nov. sp. 



(PI. 9, figs. 7 and 8.) 



Of large size. Dorsal cup subglobose ; plates heavy. Under- 

 basals of medium size, anchylosed, forming a solid pentangular 

 plate with concave sides, the latter with a somewhat waving 

 outline.^ The plate is slightly convex, except the columnar 

 attachment which is rather deeply impressed. There are abso- 

 lutely no sutures visible either upon the dorsal aspect or upon 

 the inner floor. The centre is perforated by a minute star-shaped 

 canal, with raj^s directed radially. Basals about as long as wide, 

 pentagonal in outline, but really hexagonal, the two lower sides 

 having together the length of the four others ; their upper sides 

 convex. 



Radials once and a half to twice as long as wide ; concave 

 along their basi-radial suture, along their distal side slightly 

 excavated. The articular faces are directed upward and occupy 

 nearly the full width of the plates. The articulation with the 

 brachials is by a transverse ridge with a central canal and shallow 

 fossjfi. Brachials two, both extremel}^ short but deep. They 

 are followed by several short, cuneate pieces. The upper part of 

 the arms is not known. 



The specimens show traces of interradial plates resting against 

 the inner edges of two radials, of which the places of attachment 

 are plainly visible (PI. 9, fig. 8), and detached plates were placed 

 aside of them. 



Geological Position, etc. From the Keokuk limestone near 

 Nashville (White's Creek), Tenn. The original specimens, some 

 thirty in number, are in our collection. 



^ In honor of Prof. Tratitschold of Moscow, Russia, the author of the 

 genus, who had the kindness to send us a beautiful series of the Mjatsch- 

 kowa Crinoids. 



