94 . VERTEBRARIA. 



planes of the rock, the axis, as seen in transverse section, is 

 composed of a number of compact, wedge-like sectors, radiating 

 from a common centre. Between the sectors, and sometimes 

 external to the broad faces of the wedges, a thin film of carbonaceous 

 material is found. 



In specimens preserved approximately parallel to the bedding- 

 planes, the cast, as seen in surface view, is formed of two or 

 three longitudinally disposed series of oblong or almost square 

 areas. When two series of areas only are present they are 

 separated by a longitudinal groove or ridge. Where three series 

 are found two longitudinal grooves may occur, but they are often 

 less well-marked than in the former case. In many specimens 

 the areas of one series slightly overlap those of another. The 

 areas are often striated longitudinally, the strias being fairly 

 distant. 



The areas of each longitudinal series are separated from one 

 another by transverse grooves, the grooves of any two parallel 

 series being very rarely, if ever, opposite. In most specimens each 

 area has a well-marked transverse ridge, which varies greatly in 

 position. The length of the area, i.e. the distance between two 

 transverse grooves, also varies considerably in the same series, and 

 in two parallel series. The same cast may show three series of 

 areas in one part, and only two in another. The root-like organs 

 arise at the transverse folds, and are highly branched structures. 



Vertebraria occurs in the form of casts presenting features 

 quite unlike any of the associated fossils, and much speculation 

 has arisen as to the affinities of this plant. Royle, who 

 instituted the genus, speaks of it as the " Ranigunj Reed." 

 Ennbury 1 was inclined to regard it as a root or rhizome of an 

 Equisetalian plant, a view which Peistmautel at one time also 

 shared to some extent. McCoy 2 suggested that these fossils 

 originated from plants bearing slender, jointed stems, surrounded 

 by compact whorls of six to twelve wedge-shaped leaves. All 

 doubts were, however, set at rest in 1896, when Zciller 3 discovered 

 that Vertebraria was neither more nor less than the rhizome of 



1 Bimbury (Gl), p. 339. 2 McCoy (47), p. 146. 



a Zeiller (9G 3 ) and (9G 1 ), pi. xv, figs. 8, 9. 



