VIIl] MARCHANTITES. 233 



Order Marchantiales. 



The plant-body is always thalloid, bearing rhizoids on the 

 lower surface, and having an epidermis with pores limiting the 

 upper or dorsal surface. 



Marchantites. 



This convenient generic name was proposed by Brongniart 

 in 1849^; it may be briefly defined as follows: 



Vegetative body of laminar form, with apparently dichoto- 

 mous branches, and agreeing in habit with the recent thalloid 

 Hepaticae, as represented by such a genus as Marchantia. 



The name Marchantites is preferable to Marchantia, as the 

 latter implies identity with the recent genus, whereas the 

 former is used in a wide sense and refers rather to a definite 

 form of vegetative body than to a particular generic type. 



1. Marchantites erectus (Leckenby). Fig. 49. This species 

 may be described as follows : The thalloid body is divided into 

 spreading dichotomously branched segments, obtusely pointed 

 apically. The slightly wrinkled surface shows a distinct and 

 comparatively broad darker and shorter median band, with 

 lighter coloured and thinner margins. 



In 1864 Leckenby described this plant from the Lower 

 Oolite beds of the Yorkshire coast near Scarborough, as Fucoides 

 erectus, regarding it as a fossil alga. I recently pointed out 



Fia. 49. Marchantites erectus (Leek.). From the type-specimen in the 

 Woodwardian Museum. Nat. size. 



1 Brongniart (49) p. 12. 



