328 Dr. Gr. Ogilvie on the Vascular 



ciculus with a double origin from the netted cylinder, but with- 

 out any dark sheath. 



The rhizome is of pale tissue, except the cuticular layer, and 

 one of brownish cells round the fasciculi of the netted cylinder. 



Scolopendrium vulgare. 



The petiole has two fasciculi uniting above in the midrib of 

 the frond, and separated below by two half-sheaths of dark 

 tissue, united by their convexities. Externally also the fasci- 

 culi are bordered by dark lines, which run down into the 

 rhizome. 



The rhizome is of pale tissue, except the cuticular layer and the 

 lower ends of the outer dark lines of the petioles just mentioned. 



Ceterach qfficinarum. 



The petiole has two fasciculi, which unite above in the midrib 

 of the frond, and three lines of dark tissue, which run down 

 into the rhizome — two lateral, on the outer margins of the fas- 

 ciculi, the other median, forming two half-sheaths, united by 

 their convexities. 



The rhizome is of pale tissue, except the cuticular layer and 

 the inferior extremities of the petiolar lines just noticed. 



Pteris aquilina. 



The petiole has numerous anastomosing fasciculi derived from 

 the outer and inner systems of the rhizome, also a main central 

 plaited band of dark fibrous tissue (connected with those of 

 the rhizome), and some subsidiary tracts arising within the 

 petiole. 



The rhizome has a white pulpy parenchyma, with a hard 

 cortical shell of dark tissue, and two longitudinal dark bands 

 within, separating an inner vascular system of two flat bundles 

 from a more external, which consists of numerous small fasci- 

 culi anastomosing sparingly to form an irregular wide-meshed 

 cylinder. 



Allosorus crispus. 



The petiole has a single fasciculus without a dark sheath, and 

 a double vascular cord. 



The rhizome consists in part of pale tissue, with a brown 

 cuticular layer, but it contains also dark tissue internally — as a 

 central cord along the axis, and as faintly-marked sheaths 

 round the fasciculi of the netted cylinder. 



Blechnum boreale. 



The petiole has two fasciculi, imbedded in the pale tissue of 

 the interior, which towards the base is reduced to a mere sheath 



