96 JOURNAL OF THE [JUHC, 



a fresh cross-fracture, appears to be a grayish white. This indi- 

 cates that the crystals are far from pure, probably mixed with a 

 large proportion of marcasite. 



Third. The incipient decomposition of the mineral is charac- 

 teristic of the presence of marcasite, beginning with a golden- 

 yellow tarnish within, and assuming a bronze color without. As 

 the decay progresses, the valves become covered by a reddish 

 film of iron oxide, and finally, the entire material passes into 

 reddish-brown iron-ochre, sometimes blackened, as if by the 

 intermixture of oxide of manganese. The mode of deep subter- 

 ranean decomposition is, therefore, hepatic, and vitriolescence 

 is never observed in these altered diatoms; although the latter 

 form of decay attacks the nodules of pyrites lying nearer the 

 surface in the London clay, at other points along the Thames, as 

 at the Island of Sheppey. 



In conclusion, I may state that I have found in the study of 

 pyrites, many rich and interesting fields of investigation, in 

 which the testimony of microscopical observation has proved 

 indispensable. 



THE CARPET-BEETLE. 



BY THE REV. J. L. ZABRISKIE. 

 {Read May nth, 1886.) 



The Carpet-Beetle {Anthrenus Scrophiilaricc, L.) is noted for 

 the striking colors of the mature insect and the ravages of the 

 1 irva upon our household goods. The insect was first noticed 

 in the United States in 1872, although it has been known in 

 Europe more than a century. It is now found spread over our 

 country from the Atlantic coast to California. It was doubtless 

 imported from Europe in infested carpets, and its distribution 

 has been largely traced to a certain Boston Carpet-House. 



The Beetle is about x^jth of an inch long, and prettily marked 

 with regular patches of white and red upon a prevailing black- 

 ground. It feeds upon the pollen of flowers, preferring species 

 of Spiraea. And in our locality it will be found in infested 

 houses in the latter part of April and throughout May, upon the 

 windows, endeavoring to escape to the outer air to find its food. 



The ravages are committed by the larva, which when fully 

 grown are about ^th of an inch in length, ovoid in form, and 

 thickly covered with stout black bristles, causing it to appear 



