﻿78 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 4/ 



as in D. wachsmuthi. Such a wide difference in the number of amis 

 may indicate a difference in species. There are also slight differences 

 in the surface ornament. 



Formation and locality. — Hamilton : Charlestown, Ind. 



Cat. No. 624 M. I. T. 



DOLATOCRINUS AMPLUS Miller and Gurley 



1894. Miller and Gurley, 111. State Museum Nat. Hist., Bull. 5, p. 45. 

 pi. iv, figs. 6, 7, 8. 



Formation and locality. — Hamilton : Charlestown, Ind. 

 Cat. Xo. 650 M. I. T. 



DOLATOCRINUS SALEBROSUS Miller and Gurley 



1895. Miller and Gurley, 111. State Museum Nat. Hist., Bull. 7, p. 59, 

 pi. in, figs. 13, 14, 15- 



A well-preserved specimen differs from Dolatocrinns salcbrosns 

 mainly in possessing an additional arm. The structure of the two- 

 armed ray in the type specimen of D. salcbrosns is like that of a 

 three-armed ray as far as the top of the first distichals, beyond which 

 the additional distichals and the arm are lacking from one side of the 

 ray. The normal structure of this ray is probably represented by a 

 three-armed ray, as in the specimen under consideration. The arm for- 

 mula for the latter is 1-2 ... 2-2 ... 2-2 ... 1-2 . . . 2-1, and that of 

 D. salcbrosns 2-2 . . . 1-2 . . . 1-1 . . . 1-2 . . . 2-2, from which it will 

 be seen that there is a difference in the arrangement of the arms 

 with reference to the anterior ray, but, as noted above, this feature, 

 in the genus Dolatocrinns, cannot be considered of value for specific 

 determination. 



The presence of respiratory pores has not been determined for the 

 type, but they are plainly visible in the specimen studied. 



Formation and locality. — Hamilton: Charlestown, Ind. 



Cat. Xo. 656 M. I. T. 



DOLATOCRINUS EXCAVATUS Wachsmuth and Springer 



1897. Wachsmuth and Springer, Nortli Amer. Crinoidea Camerata, p. 

 321, pi. xxv. fig. 1; pi. xxxvi, figs. 7, 8. 

 An individual retaining the lower portion of the dorsal cup only, 

 has been identified with this species. The species is closely related 

 if not identical with D. grandis Miller and Gurley. The chief 

 difference seems to be the presence of sharp carinse on the lower 

 brachial plates of P. cxcazvtus. These are not mentioned in con- 

 nection with D. grandis, but the basal depression of the type of that 



