A HERPETOCRINUS FROM THE SILURIAN OP IOWA 483 



are almost pure quartz. The crown unfortunately is not well 

 enough preserved for detailed study. The evolute and involute 

 parts of the stem are so preserved as to show very well the relation 

 of the two parts and the way in which the crown is tucked away in 

 the concavity of the crescentic stem is better shown than would be 

 the case were the cirri present. The Henley specimen preserves 

 about a coil and a half of the involute part of the stem. This por- 

 tion shows very well the cirrus-articulations, the position of the 

 lateral sutures, and other features. 



As stated above the specimens were collected in the Silurian (Ni- 

 agaran) beds near Monticello, Jones county, Iowa, where they are 

 associated with Petalocrinus mirahilis, Pisocrinus sp., Goniophylhim 

 pyramidale, and others. These forms together with Herpetocrinus 

 occur also in the Silurian rocks of the island of Gotland in the Baltic 

 sea. The similarity of these two widely separated faunas has been 

 pointed out by several writers. Herpetocrinus has been reported 

 also from the Silurian of the Chicago area, from Tennessee, from 

 New York, and from England. Later visits to the Monticello local- 

 ity have not netted a trace of this crinoid in spite of most diligent 

 search. It is evidently somewhat rare. Effort has been made to 

 identify the material with some of the species already described but 

 no definite report can be made at present. 



The Department of Geology, 

 The State University. 



