292 



GENERAL REMARKS. 



otherwise limited to the immediate covering, partial or com- 

 plete, of the capsula externa. 



Plagiochasma is a remarkable genus, it is the only one in 

 which the peduncle is not a continuation of the apex of the cen- 

 tral vein : hence it is not exserted from the sinus, but passes up 

 from the vein, and through the substance of the frond itself. 

 Neither has it the structure so characteristic of the others, as the 

 overlying structures are not carried up, so to speak, with it. 

 I have hence described the capsules as stipitate. It is fur- 

 ther remarkable for the presence of elaters, and the absence of 

 fibrous cells of the capsule, of this want of assimilation, it is 

 the second instance in this collection. 



Askepos is an obscure genus, and described from imperfect 

 materialise as I have not seen the mature capsules. 



Monosolenium is chifly remarkable for the very distinct 

 remains of broken up cells that surround the sporula, at least 

 in their younger stages. 



Octoskepas is perhaps singular in the nature of the inner 

 involucrum, which at an early period is only quadrivalvular, 

 the valves subsequently becoming divided. 



Synhymenium is worthy of notice on account of the valvular 

 dehiscence of the capsule, although it is incomplete, and for 

 the membrane by which the valves, at first four in number, 

 are originally held in connexion. It is curious too, that the 

 fibres only exist in the cells forming the valves themselves. 



Anthoceros presents so many peculiarities, that I shall be 

 excused for entering into its consideration at some length, 

 so far at least as regards the female organs. The first indica- 

 tion of the developement of these, consists in the appearance 

 of a convexity on the upper surface of the frond, which is at 

 once distinguished by a sort of lucid whitish appearance. Over 

 this convexity, is spread an excessively fine membrane (to the 

 existence to which the lucid appearance is probably to be at- 

 tributed) which at the centre of the convexity is inflected in- 

 wards in the shape of a process resembling a good deal the 

 beak of a funnel. The extent to which this process pene- 



