203 



The genus Lampterocrinus of Roeiner, 1860, is appa- 

 rently identical with the genus Balanocrinus of Troost. 

 The latter name was first published in Troost's Catalogue 

 in 1849. 



The group of species referable to these genera is a very 

 interesting one, and the following species contribute some 

 farther information in relation to their geological distribu- 

 tion. 



The following, and all the species included in this 

 paper are from the bluish gray shales of tJie age of the 

 Niagara group near Waldron, Indiana : 



GENUS GLYPTOCRINUS (Hall). 



GLYPTOCRINUS CARLEYI {Hall). 



General form of body turbinate pentangular, the angles 

 coincident with the rays and marked by a rounded ridge, 

 the intermediate spaces concave. The upper disc of the 

 column is marked by five divisions indicating the unde- 

 veloped basal plates; subradial plates (or basal plates of 

 the generic description), wider than high, each one 

 marked by a single or double rounded radiating ridge. 

 Radial series strongly marked by a longitudinal rounded 

 ridge which bifurcates with the first and second division 

 of the ray, giving four arms to each ray as they leave the 

 body. Besides the longitudinal ridge the plates of the 

 radial, interradial and supraradial series, are marked by 

 sharp radiating ridges with the intermediate spaces 

 finely granulose. Rays bifurcating on the third plate and 

 again on the second plate of the supraradial series. In- 

 terradial plates eight or more (probably ten or twelve) 

 with several intersupraradials. 



In form this species resembles the G. decadactylus of the 

 lower silurian strata, but is proportionally shorter and a 

 little more rapidly expanding. The radiating ridges upon 



