Species of Cycadeoidea from Maryland. 9 



trically arranged bracts or scales whose scars were last described. The 

 spadix has a receptacle at the base, located near the inner surface of the 

 armor and supplied with fibers from the axis. From the receptacle there 

 rise two kinds of organs, first, peduncles or filaments, known in a few 

 specimens to bear seeds and conjectured in one specimen to bear anthers 

 at their summits, and, second, elongated chaff-like scales more numerous 

 than the latter and rising above them, the upper portions expanding and 

 forming a dense mat or covering over the essential parts. In most cases 

 all these organs are wholly included in the armor, the only seeds that 

 have thus far been found being deeply embedded in the tissues. The 

 organs of inflorescence are probably axillary, but owing to the proximity 

 of the leaf scars this is not generally apparent. In regions of the surface 

 where they occur they usually crowd the leaf scars and cause variations 

 in their shape. This effect is most marked on the upper sides of the 

 scars, often quite obscuring or obliterating their normal features. 



The axis of the trunk inclosed in the armor when complete consists of 

 four parts, which, enumerated from without inward, may be denomi 

 nated respectively as (1) the libro-cambium, (2) the parenchymatous 

 wood, sometimes called the cortical parenchyma, (3) the wood proper or 

 fibro vascular zone, and (4) the medulla or pith. In many cases the libro- 

 cambium zone cannot be definitely distinguished from the cortical paren 

 chyma, and nothing is visible but the large and numerous vascular bun 

 dles passing out from the interior into the leaves ; but sometimes there 

 occurs a definite line or thin zone of loose tissue immediately below the 

 bases of the leaf stalks. There is usually a zone of apparently homoge 

 neous cellular tissue, often of considerable thickness, filling the interval 

 between the armor and the woody axis. The woody zone consists of one 

 or more rings of exogenous tissue traversed by medullaiy rays. Where 

 more than one, they are separated by thin interstices of parenchymatous 

 tissue. The medulla is usually large and composed of coarse parenchyma. 



Cycadeoidea Marylandica (Font.) Cap. and Solms. 



18(>0. Ct/cas sp. Tyson, First Report State Agric. Chem. Maryland, p. 42. 

 1870. Bennettites sp. Carruthers, Trans. Linn. Soc. London, vol. XXVI, 



p. 708. 

 1879. Cycadeoidea sp. Fontaine, Am. Journ. Sci., 3d ser. , vol. XVII, p. 



' 157. 

 1889. Tysonia Marylandica Fontaine, Potomac or Younger Mesozoic Flora, 



Monogr. (l. S. Geol. Survey, vol. XV, p. 193, pi. clxxiv-clxxx. 

 1892. Cycadeoidea Marylandica (Font.) Cap. and Solms, Mem. Real. Accad. 



Sci. 1st Bologna, ser. V, torn. II, pp. 179, 180, 186. 



Trunks of medium or rather large size, almost always more or less later 

 ally compressed so as to be elliptical in cross section, conical in shape or 

 slightly narrowed near the base with a terminal bud set in a slight de 

 pression at the summit, simple, or in one specimen, apparently having 

 one branch ; mineral constitution very variable according to mode of 

 preservation, but usually not hard, flinty, or heavy and compact ; reddish, 

 pinkish, drab, or ash colored ; 25 to 45 centimeters high, 24 to 40 centi- 



2 HIOL. Soc. WASH., VOL. XI, 1897 



