1858.] BINNET STIGMARIA. 79 



figured at fig. 4, or the bases of the cavities in the figures in plate 1. 

 This very simple structure of rootlet is similar to that of several 

 Lycopodia, and indeed of many other plants, both Monocotyle- 

 donous and Dicotyledonous, so far as can be ascertained without a 

 farther knowledge of the axis of the organ ; of the structure of 

 which, however, there can exist no reasonable doubt, since it may 

 be confidently assumed to consist of a bundle of vessels, similar to 

 those represented at fig. 7a." 



The specimen of the rootlet oiStigmaria now about to be described, 

 was found by me during the last summer on an old coal-pit hill at 

 Over Darwen, Lancashire ; it occurred in a nodule of clay-ironstone, 

 most probably derived from the roof of one of the lower seams of 

 that district. The rootlet from which my sections have been made 

 was from a part about half an inch from the root ; it is quite cylin- 

 drical, and was originally one-fourth of an inch in diameter, but 

 since its fossilization it has diminished one-half, probably owing to 

 the removal of its thick carbonaceous exterior. The remaining 

 eighth of an inch is for the most part composed of crystallized 

 mineral matter (silica most probable) ; and it is only a small circu- 

 lar speck, of about one-thirtieth of an inch in diameter, in the 

 centre of the rootlet, that affords structure. With the assistance of 

 Mr. Cuttell, I have been able to obtain a good transverse, and a 

 moderately fair longitudinal, section of this small specimen. 



First as to the transverse section. Its exterior consists of a ring 

 of very fine cellular tissue three or four cells broad. This is suc- 

 ceeded by a space, about five times the diameter of the ring above 

 named, in which no structure is apparent ; the fine tissue having 

 disappeared : then in the centre is a beautiful pear-shaped mass of 

 vascular tissue, one-ninetieth of an inch diameter, consisting of 27 

 large vessels, having hexagonal, pentagonal, and other openings, and 

 of a bundle of 11 very minute nearly circular vessels at one extre- 

 mity, as shown in Plate lY. fig. 4, in the transverse section. 



The longitudinal section, Plate lY. fig. 5, is not true, being about 

 half-way between a transverse and a longitudinal section ; but it 

 clearly shows that the vascular utricles or vessels were marked with 

 transverse striae on their different sides, and, although of such minute 

 dimensions, corresponded with the vessels found by M. Brongniart 

 in Sigillaria elegans, and similar to what Dr. Hooker supposed they 

 would be, although probably considerably smaller in size. 



The appearance of the vessels in their transverse section, both the 

 large and small ones, remind me of the section of a root of Asjoidium 

 exaltatum figured by M. Brongniart, in plate 8 (xxxii.), fig. 10 of 

 that learned author's " Observations sur le Sigillaria elegans,'''' ex- 

 cept that the vascular bundle of my specimen is somewhat pear- 

 shaped, and not irregular stellate, as in the transverse section of 

 Aspidium. 



EXPLA]!^ATION OF PLATE IV. 

 Fig. 1, «. A portion of the woody cy finder of Stigmaria ficoides, jDresenting a 

 transverse section, and showing the orifices through which the medul- 

 lary rays or bundles passed from the centre of the root to the exterior. 

 Natural size. 



