l82 NEW YORK STATE MUSEUM 



PLATE 6 



iCaryocrinites ornatus Say, a cystid having a 

 small gastropod (Strophostylus) attached and covering 

 the apertures of the summit. From the Upper Siluric 

 (Rochester) shale of western New York 



2 Glyptocrinus (decadactylus Hall) with a 

 holostomatous gastropod, Cyclonema bilix, in- 

 closed within the arms in an attitude of feeding at or 

 near the anal aperture of the crinoid. From the Cincinnati 

 shale 

 3,4 Cromyocrinus simplex with attached Platyceras 

 of relatively large size, its anterior portion covering the 

 anal aperture of the crinoid while the rest of the lip 

 of the snail extends over the entire hight of the calyx. 

 Carbonic limestone, Moscow, Russia 



5 Platyceras enveloping the dome of Arthracantha 



punctobrachiata Williams [after Hinde, Ann &. 

 Mag. Nat. Hist. 1885]. From the Hamilton group 



6 A part of the tegmen ofStrotocrinus regalis Hall 



showing the successive growth marks made by an attached 

 Platyceras, always keeping its anterior extremity over 

 the anal aperture of the crinoid [after Keyes, Acad. Nat. 

 Sci. Phila. Proc. 1890. pi. 2, fig. 7]. From the Carbonic 

 (Mississippian) of Crawfordsville, Ind. 



7 Platyceras infundibulum Meek & Worthei 



attached to the anal surface ofPlatycrinus hemi 

 sphericusM. &W. [after Keyes ut. cit. fig. 10] 



8 Actinocrinus multiramosus Wachsmuth & Springer.* 



The calyx with a starfish (Onychaster) fastened to the 

 anal tube [after Wachmuth & Springer ut cit. pi. 55, fig. 3] 



