NATURAL SCIENCES OF PHILADELPHIA. 85 



profusely filled with plants thrown up from the creeping stolons. 

 This gave an average of about three-fourths of an inch of growth 

 per day ; equal to maize or other rapid-growing vegetation above 

 ground. 



June 9. 

 * Prof. Jos. Leidy in the chair. 



Sixteen members present. 



Prof. Persifor Frazer, Jr., made the following remarks : 

 During a recent trip to Missouri I had an opportunity of visit- 

 ing and personally examining the Pilot Knob, and Iron Mountain, 

 and Mine La Motte districts, in company with two of the assist- 

 ant geologists Prof. Potter and Mr. Gage. There is much in 

 this district, and in fact in most parts of Missouri, to interest 

 the student of geology from east of the Alleghanies: for example, 

 the variations in the character of the porphyry, which is the 

 archpean according to Prof. Pumpellj^ or the azoic member of the 

 Missouri series. This porphyry carries several deposits of ore, 

 both veins and beds, as has been ably pointed out in the recent 

 geological survc}^ of the State by Prof. Pumpelly. Tliis, and the 

 magnesian limestones which overlie it, form the principal part of 

 the surface in the southeastern part of the State. 



Mine La Motte is situated in St. Francois County, about ninety 

 miles nearl}'^ due south of St. Louis. There are extensive works 

 put up on this property, and the whole was sold to an English 

 company two j^ears ago for $.3,000,000, but the sale could not be 

 ratified owing to a law of Missouri which prohibits foreigners 

 from holding property in tiiat State. At least such was the in- 

 formation given to me. The deposits of lead and copper and 

 nickel ores at Mine La Motte, part of a great belt about one hun- 

 dred miles wide which crosses the State from southeast to north- 

 west, lie in the limestone. At Mine La Motte there is a pro- 

 fuse occurrence of nickel-bearing minerals, and especially of 

 millerite, which is found in stellate, acicular, and radial crystals 

 on the sui'face of many of the lumps of ore. 



The works here, before they were burned down, treated the 

 ores in open American hearths, and brouglit out matt wliich was 

 shipped to Swansea. It is said, on competent authority, that a 

 galena exhibiting a peculiar blue color (like that found on the 

 surface of much peacock ore), contains cobalt. The cause of this 

 color, and also its connection with the contained metal, are not 

 perfectly understood. Abnost all of the galena of the district is 

 colored in this way. 



I present also specimens of iron ore from Iron IMountain, 

 Missouri, where it occurs in irregular veins, intersecting the por- 



