wherry: cavities in zeolite deposits 181 



The matrix in which the plants is preserved is a white, fine- 

 grained, shaly sandstone, well fitted to retain the details of 

 nervation, and there can be no question as to the identification. 

 The two species present are: Nilsonia nigricollensis Wieland 3 

 and Zamites arcticus Goppert. 4 The first species has previously 

 been found only at its type locality in the lower part of the 

 Lakota sandstone, near the summit of the Black Hills rim, 5 

 miles north of Sturgis, South Dakota. The other species 

 (Zamites arcticus) is very abundant in the Kootenai of Montana, 

 and several Canadian localities. It has been reported also 

 from the so-called Shasta flora of California, and from the Kome 

 (Urgonian) of Greenland. 



While it is manifestly unsafe to build much of a generalization 

 on two species, yet so far as they go they indicate that the 

 Morrison is Cretaceous. 



A word may be added as to the evidence to be derived from 

 the cycad trunks above mentioned from the Freezeout Hills. 

 Although they are referred to a distinct genus (Cycadella) they 

 are certainly very close to, if not indeed identical with, similarly 

 silicified trunks of the genus Cycadeoidea, which are so abundant 

 in the Lakota sandstone of the Black Hills rim and which occur 

 also in the Patuxent formation of Maryland. The internal 

 structure has not been fully investigated in Cycadella, about the 

 only obvious difference between it and Cycadeoidea being the 

 profusion of ramentum in the former, which is a character of 

 doubtful generic value. This evidence also — so far as it goes- 

 argues for the Cretaceous age of the Morrison. 



MINERALOGY. — The lozenge-shaped cavities in the First Watch- 

 ung Mountain zeolite deposits. Edgar T. Wherry, Na- 

 tional Museum. 1 



The zeolite deposits in the basalt of First Watchung Mountain 

 in Passaic County, New Jersey, frequently contain angular 

 cayities representing minerals which crystallized out at an 



3 Wieland, G. R., in Ward: U. S. Geol. Survey Mon. 48, 319, pi. 73, figs. 15a-d. 

 1905. 



4 Op. cit., 306, pi. 73, figs. 1-6. 



1 Published by permission of the Secretary of the Smithsonian Institution. 



