ON HEHATICiE. 



295 



The genera to which the Affghan plants of this family 

 appear referrible are Targionia, Plagiochasma, Reboiullia, 

 Marchantia, and Jungermanniae. Plagiochasma, I suspect 

 will subsequently absorb Antrocephalus.* 



Ricciacese are remarkably distinct, in having the spores 

 contained in a capsule, (the original pistillum) not a secon- 

 dary development as in all the genuine plants of the family 

 known to me, and which consequently would be described 

 as having no calyptraf, I find two distinct modes of develop- 

 ment of the peduncle. In one, and this is very evident in 

 marchantia, the peduncle is a narrow elongation from the 

 apex of the frond, with which its surfaces correspond re- 

 markably in structure. And tho* in some as in Reboiullia, 

 the whole substance of the frond would not appear to be 

 continued in the peduncle, judging from the absence of aera- 

 ting cavities and organs on the face corresponding with the 

 upper surface of the frond, yet I have not met with any in 

 which the capitulum is not manifestly a part of the frond, 

 and which do not present one furrow at least in the ventral 



* This genus, Antrocephalus, is identical with a mss. genus, Asoleni- 

 ura, which I sent home to my friend Mr. R- H. Solly in 1836-7. 



f This term should be discontinued: it is obviously a contradiction 

 in terms, and besides, does away, technically, with one of the greatest 

 distinctions between Hepaticae and Musci. It is applied in the latest 

 works with great laxity. In Ricceaceae (Endlich. Genera) it is applied 

 to an involucrum, while the sporangium is described as terminated by a 

 persistent style, which at once shews that it is the Calyptra, or the Pisti- 

 lam. 



In Anthoceros, as I have said, 1 believe it to be applied to a dislocated 

 part of the tissue of the frond itself. 



In the above most useful and excellent work, I may add, none of the 

 diagnostic marks (p. 43, sub Hepaticae : p. 46 sub Musci) between Hepa- 

 ticae and Musci, are free from exception. In Sphagnum the calyptra does 

 not separate by its base, but is lacerated by the cupsule growth, as in 

 Marchanteaceae. Jungermannia is vaginulate, Anddraea has no oper- 

 culum, and lastly, many Marchanticeae do not present elaters. 



