RHYTIDOLEPIS FIBROSA. 



FIBRO US RH YTIDOLEPIS. 



Generic Character. 

 Stem simple, furrowed ; furrows wavy, impressed with dots or simple lines placed 

 on the ridge. 



Specific Character. 

 RHYTIDOLEPIS fibrosa. Cicatrices ovate, subpentagonal, with a single 

 gland; surfaces of the ridges fibrous. 



Synonyms. 

 This species has not been found described, or figured, in any work on fossil plants. 



Description and Locality, 



Stem simple, cylindrical, (sometimes pressed flat) furrowed longitudinally, 3 feet 

 long, and 4 inches in diameter ; terminating abruptly. 



Furrows small, ridges semicircular, wavy, being enlarged round the cicatrices; 

 surface fibrous. 



Cicatrices on the top of the ridge, ovate subpentagonal with the lower angles 

 rounded, having a single gland near their lower rounded extremity. 



Found vertical, in the sandstone of a quarry at Rowmarsh, near Rotherham in 

 Yorkshire. 



A very similar fossil is also found in the El-se-car coal mine, near Wentworth ; 

 but these specimens are usually pressed flat, and have the external membrane bitu- 

 minized : in consequence of this pressure the undulation of the ridge forms a trans- 

 verse line, which gives the stem a tessellated appearance, especially near the upper 

 extremity where the cicatrices are closer together than at the lower end. • 



The section of this species, which has never as yet been found with any traces of 

 bark upon it, as exhibited in fig. 1, shows, by its double concentric ring, some slight 

 appearance of internal organization, which also appears in some degree by the fibrous 

 striae of the surface of the ridges, resembling that of some species of wood. Fig. 2, 

 shows the great equality of the stem throughout its whole length and its abrupt ter- 

 mination. Fig. 3, expresses the cicatrix with its single gland, on which the leaf was 

 probably inserted : and the 4th figure shows the wavy line formed by the top of the 

 ridge. 



Observations. 



Of the fossil plants hitherto figured, that which comes nearest to this species, is 

 the Rhytidolepis ocellata of Count Sternberg in his 15th plate; but the form of the 

 cicatrix is different. 



Dr. Martins is doubtful whether the plant figured in the Count's plate should 

 be considered as one of his cactites or euphorbites. 



