THE MARYLAND CYCADS. 415 



emplo3^ed by the residents in describing them. A few of the fragments are 

 suggestive of considerable elongation not unlike that of the modern 

 Cycas revoluta or Macrozamia. In these cases, however, the shape of the 

 trunk appears to be governed to some extent by the food supply— uni- 

 formity producing a regularly cylindrical trunk, and want of it an irregular 

 conical one. 



The so-called "crow's nest" is in a few cases very well defined. The 

 best of these occurs in the Turner trunk (PI. XCV), which, as already 

 stated, was long in use as a watering trough for domestic fowls. 



The considerably weathered and etched condition of the fractured 

 surface of most of the fragments indicates that the fractures are of con- 

 siderable age. This conclusion receives some confirmation by the fact 

 already suggested that, save in a single instance (W. C. B. Nos. 1659 and 

 1659a), a second fragment has never been found near the first. In the 

 case of the exception the fracture is evidently not recent, as supposed 

 by the plowman who unearthed it, and this is the only instance in which 

 two fragments have ever matched together. 



The color of the trunks is identical with that of the silicified coniferous 

 wood which is not unfrequently associated with them. When newly 

 unearthed they are light and dark buff to reddish brown or brownish red, 

 dependent upon the amount of hydrous iron oxide present in their original 

 or secondary beds. After exposure to the weather for some time they 

 are apt to assume darker tints — light and dark gray being the most 

 common. 



Respecting the frequency of occurrence of the Potomac cycad trunks, 

 it should be stated that, while the number of specimens which have been 

 brought to light within a comparatively short time is considerable, this 

 is due rather to the adoption of a successful method of searching than 

 to the actual abundance of the fossils. They are really so scarce that there 

 is little chance of one being secured from the field by direct search-. No 

 one, in fact, has ever been known to do this, all having thus far been 

 found by accident. It is rarely that more than one trunk has been noted 

 in a given locality, but there are a few notable exceptions to this rule. 

 Though the cycad trunks are of considerably less frequent occurrence 

 than the silicified trunks of conifers, it may be said that there was a 

 goodly showing of the cycadaceous vegetation in the forests of Potomac 

 times. 



