Species of Cycadeo idea from Maryland. 7 



usually simple, but sometimes branching, with a depression at the sum 

 mit, in the middle of which, when not decayed, there is a terminal hud 

 of conical shape ; terminal bud, however, usually wanting in the fossils, 

 leaving a cavity commonly known as the "crow's nest," by which name 

 for this reason the specimens from the Portland quarries are popularly 

 known. The armor consists of appendicular and reproductive organs 

 surrounding and enveloping the axis, the former being the bases of the 

 leaf stalks or petioles, which are surrounded by a dense mat of ramentum 

 or fine hairs. 



The leaf stalks are normally four-sided and four-angled, the lateral 

 angles acute and nearly equal, the vertical angles obtuse but unequal, the 

 lower much sharper than the upper, so as to render the cross section sub- 

 rhombic. This form varies on the one hand to a true rhomb, and on the 

 other hand to a true triangle, the most frequent intermediate type being 

 that in which the upper angle is wanting, and the two upper sides are re 

 duced to a simple curve or arch, so that the cross section assumes the form 

 of a drawn bow and bowstring, the arch formed by the two upper sides 

 representing the bow and the two lower sides, with their reentrant angle, 

 representing the bowstring. In size the leaf stalks vary from 15 to o5 

 millimeters in width measured between the lateral angles, and from 5 to 

 20 millimeters in height measured between the vertical angles, or from 

 the lower angle to the summit of the arch formed by the two upper sides. 

 The line joining the former is not generally horizontal or at right angles 

 with the axis of the trunk, but one is usually slightly lower than the 

 other. The line joining the latter is not generally vertical or parallel to 

 the axis of the trunk, but one is usually a little on one side of the other. 

 The only portion of the leaf bases that is always preserved in the fossil 

 state is the mat of ramentaceous hairs that surrounds them. In the great 

 majority of cases the petioles themselves are decayed to a greater or less 

 distance below the summit of these mats, which thus constitute walls 

 surrounding and enclosing the portion that remains of the petioles, if any, 

 and in their absence forming definite cavities having the shape of the 

 cross section of the leaf stalks, which constitute the leaf scars. These 

 leaf scars, with or without the lower portion of the leaf bases, penetrate 

 to the axis of the trunk and form a varying angle with it. Normally this 

 angle is a right angle overall the central portions of the trunk, while 

 below r the organs are slightly descending and above more and more as 

 cending to the apex, where they become vertical. At the summit, too, 

 they diminish in size and usually in form, and are reduced in and imme 

 diately around the terminal bud to small triangular or polygonal bracts 

 (peruhe of Miquel). In some species (C. Uhleri) all the organs of the body 

 of the trunk are deflexed, and in one (C. Goucheriana) there is a definite 

 zone near the middle of the trunk, below which they are descending and 

 above which they are ascending. The leaf scars are arranged in a more 

 or less exact quincunx order, and usually in two sets of spiral rows around 

 the trunk, in one of which they ascend from the base in the direction 

 from left to right and in the other from right to left, crossing each other 

 at varying angles, and both rows making a certain angle with the axis of 



