1892.] NEW-YORK MICROSCOPICAL SOCIETY. 59 



tions made by Dr. Julien, that the formation in which the wood 

 is found is of considerable extent, and has been traced in New 

 Mexico and Arizona for some hundreds of miles, and had been 

 referred to the Chinarump Group of the Jura Trias by Major J. 

 W. Powell. My observations of the locality lead me to the con- 

 •clusion that silicious water was the silicifying agent. The trees, 

 having fallen into water, had partly rotted, and only after sink- 

 ing in the swamp, lake, or river had silicification set in. The 

 trees on the lower levels in the so-called parks did not really 

 belong there, nor had they come from any of the layers of 

 rock from the same level, but from the top strata, in some places 

 one hundred feet above where they lie at present. I observed 

 trees in situ only in this upper layer. One tree in situ measured 

 over one hundred feet in length. From the total absence of 

 roots and branches and bark, I conclude that the wood had not 

 been silicified in the same manner as the agatized woods of Yel- 

 lowstone Park and Colorado, where the logs or trees are gene- 

 rally hollow, inasmuch as all the Arizona trees must have silicified 

 in a recumbent position, having fallen in some unknown lake, sea, 

 river, or swamp. And, further, that as there was no bark on any 

 of the trees, they must have rotted, and in some of the masses ex- 

 amined at least four or five inches of the bark and outer rings 

 of the tree were missing. They were silicified in water highly 

 charged with oxide of iron, the red or yellow color varying ac- 

 cording to the amount of oxide present, probably by decomposi- 

 tion of a variable amount of vegetable matter. The presence of 

 the fungus zooglia, described by Dr. Julien, has probably induced 

 the precipitation of silica from the water in which the tree trunks 

 lay." 



Mr. Zabriskie said of his exhibit : "This small parasite, col- 

 lected at Fisher's Island, L. I., is one of the most curiously 

 formed parasitic wasps of our fauna. The slender petiole of the 

 abdomen, instead of being placed in the usual position, is in- 

 serted high up on the back, at the base of the metathorax. The 

 abdomen is greatly compressed, and the area of its side is only 

 one-fourth of the corresponding area of the thorax, causing the 

 abdomen to appear ridiculously small. The anterior wings 

 possess only one cell — the costal cell — and are furnished with 

 costal, subcostal, and basal nervures, and with a prominent 



