4 1 <S MESOZOIC FLORAS OF UNITED STATES. 



armor thin, 2 to 5 cm., usually joined to the internal parts by a clear 

 line, but without measurable thickness, but sometimes ver}^ irregularly 

 so joined and occasionally showing a thin libro-cambium layer; woody 

 zone 3 to 10 cm. thick, usually with two or three more or less distinct 

 rings, the outer or parenchymatous zone thicker and firmer than the 

 inner or fibrovascular zone; medulla usually homogeneous in structure, 

 elliptical, the major axis 8 to 17 cm., the minor 3 to 9 cm. 



This is historically the most important species of Maryland Potomac 

 cycads, most of the original types found by Tyson belonging to it. It 

 is also the most abundant species, the whole number of trunks and frag- 

 ments now known amounting to 28, an increase of 10 since 1897, when 

 I was able to record 18 specimens. To this species also belongs the Link 

 trunk, the only one that has been actually seen in place. 



The following is the list of these 28 specimens, chiefly in the order of 

 their discovery, as denoted by the numl^ers assigned to them in the 

 different institutions to which they belong, and accompanied by their 

 vernacular and folklore names, so far as they have received such, and by 

 their weights expressed in kilograms and decimals of kilograms, with the 

 abbreviations described on page 751a: 



Weight in 

 kilograms. 



J. H. U. Cycads, No. 1 _■ 40. 37 



J. H. U. Cycads, No. 2 24.94 



J. H. U. Cycads, No. .3 3. 18 



J. H. U. Cycads, No. 5 10. 89 



Md. Acad. Cycads, No. 1 18. 14 



W. C.,B., No. 1192, the Tubbs fragment 3.74 



W. C, B., No. 1428, the Crook fragment. No. 1 8.39 



W. C, B., No. 1481, the Link trunk 18. 14 



W. C, B., No. 1486, the Harrison fragment ("wasp's nest") .47 



W. C.,B., No. 1656, theR.T. Donaldson fragment, No. 2 .79 



W. C.,B.,No. 1657, theD. O. Donaldson fragment . .45 



W. C.,B., No. .3050, the Harwood trunk 7.03 



W. C.,B.,No. 3051, the Morgan trunk 2.72 



W. C, B., No. 3056, the Lester trunk 7.03 



W. C, B., No. 3057, the Owens fragment . : 4.20 



W. C.,B.,No. 3324, theR.T. Donaldson fragment, No. 3 9.74 



W. C, B., No. 3328, the Helwig trunk 11.79 



W. C, B.,No. 3.341, theR.T. Donaldson fragment, No. 6 _. _. 2.72 



W. C.,B.,No. 6.343, the R. P. Disney trunk, _.. , _• 4.55 



