106 REPORT— 1873. 



On Fern-stems and Petioles of the Coal-measures. 

 By Professor "W. C. Williamson, F.R.S. 



The author described the structui-e of several stems of Calamites and Lycopodia- 

 ceous plants from the Coal-measures, in which a thick vascular zone intervened 

 between a central pith and an outer hark, and which zone increased in thickness 

 by successive additions made to its external surface through the genetic agency of 

 the innermost layer of the bark. Adopting these plants as typical representatives 

 of a condition wholly unknown amongst living Cryptogams, he called attention to 

 a series of stems from the Coal-measures which bore the appearance of being the 

 petioles and rhizomes of ferns. One of these, to which he had previously assigned 

 the provisional name of Edraxylon, he now showed to be an undoubted fern, since 

 he has obtained it with leaflets attached to it. This plant proves to be one of the 

 species oi Pecopteris in which the rachis and petiole is covered with minute tubercles, 

 as in some recent Cyatheas. After examining a series of other stems, including the 

 Stauropteris of Binney and the Zygopteris Lacatti recently described by M. Renault, 

 he examined the Palmacites carbonigcmis of Corda, and which latter has generally 

 been regarded as a palm. The avithor rejected this view, and came to the conclu- 

 sion that the plant was a fern allied to the Marattiacere of the present day. In none 

 of the above plants was the slightest trace of the exogenous growth so common 

 amongst the Lycopods and Calamites to be found. But the author thought it pro- 

 bable that the Heterangimn Grievii, recently described by himself in a memoir 

 now being printed by the Royal Society, and in which a very feeble attempt at the 

 development of such a growth was observable, might prove to be a fern. But even 

 in that case the instance was such an isolated one, so far as our present knowledge 

 extends, and the growth was so feebly developed, that it merely appeared like one 

 of those exceptions which prove the rule. It only indicated the aJjsence in nature 

 of those sharply defined boundary lines which the systematist is ever seeking to 

 establish, but within which nature refuses to be restrained. 



On the Flora of the Environs of Bradford. By Dr. Willis. 



Zooxoor. 



On some Recent Results ■with the Towivrj-nci on the South Coast of Ireland. 

 By Professor Allman, F.R.S. 



1. Mitraria. 



Only a single specimen was obtained of the little Mitraria which formed the 

 subject of the present communication ; and neither its structuie nor development was 

 made out as completely as could have been wished. From the Mediterranean species 

 described in a former communication (British Association Report for 1872), it differs 

 in some points of structure and in the mode of annulation of the developing woim. 

 It possesses the usual Miiraria-iorm — that of a hemispherical dome, having its 

 base encircled by a band of long vibratile cilia. In the side of the dome, a little 

 above the ciliated band, is the moiith, which leads into a rather wide pharynx 

 clothed with a ciliated epithelium. The pLnrynx runs through the dome parallel 

 to its base, and opens into a capacious stomach, which continues in the same direc- 

 tion until it joins the intestine. This then turns down abruptly at right angles to 

 the previous portion of the alimentary canal, and then projects for a short distance 

 beyond the base of the dome, caiTying with it, hernia-like, the walls of the base. 



The true body-walls of the future worm, of which the Mitraria is the larva, seem 

 as yet confined to the intestinal segment of the alimentary canal. They already 

 present the commencement of annulation, which, however, exists only on the 

 dorsal and ventral sides ; while two broad bands of very distinct fibres may be seen, 



