TOSSIL FLORA. 37 



PLATE X. 



(Plates X. to XXXIV. inclusive, are from Artis's work on the Fossil Remains of Plants, from the coal formations 



of Great Britain.) 



" Columnar Hydatica." 



Under the name Hydatica, Mr. Artis has described two species of fossil plants, from the coal- 

 mine near Wentworth, Yorkshire. The originals appear to have been aquatic plants, having a 

 horizontal or creeping stem, sending up slender branches, which floated by their leaves on the 

 surface of the water. 



The generic characters are, " Stem, arborescent, jointed, branched ; leaves, long, linear." 



In the arrangements of Schlotheim and Brongniart, who consider only the construction of 

 the leaves, these plants would belong to the genus Poadtes. 



The species figured is named Hydatica columnaris, or Columnar Hydatica. The stem is 

 branched all the way up, and ends in a club-like head ; the branches are numerous, simple, 

 alternate, and covered with parallel hair-like leaves. 



Fig. 1. The plant of the natural size, imbedded in coal-shale; fig. 2, a branch magnified, 

 showing; the two linear series in which the leaves are arranged. 



