APPENDIX 619 



Two theories have been advanced. Cavers believes all of the 

 Acrogynas have arisen from the same type, and of the existing Anacro- 

 gynse he thinks Fossombronia represents most nearly this hypothetical 

 ancestor. 



Spruce (2) has argued that there is good reason to separate the 

 Acrogynae into two series, one Jubuloideas (= Lejeuneacese), which 

 perhaps arose from Metzgeria-like ancestors ; and the Jungermanneae 

 (including all the other Acrogynae), which have been derived from 

 forms like Fossombronia. 



Fossombronia differs a good deal from the typical Codoniaceae, and 

 shows some suggestive resemblances to the Sphaerocarpales, especially 

 to Geothallus. Petalophyllum is another genus, usually referred to the 

 Codoniaceae, which is also perhaps related to Geothallus. It is possible 

 that there is a distinct series of related genera leading from Geothallus, 

 through Petalophyllum and Fossombronia, to Treubia. The latter, 

 on the whole, probably comes nearest to the typical Acrogjmae. 



P. loi. The archegonia are not necessarily confined to special 

 branches, but in some genera, e.g., Plagiochila, Gottschea, are borne 

 at the apex of the main axis. In most genera several archegonia are 

 formed before the apical cell is transformed into an archegonium, but 

 in Lejeunia a single archegonium only is present, and in FruUania 

 usually two. 



The archegonial group is usually surrounded by an outer sheath 

 (perichaetium) composed of a whorl of more or less concrescent 

 leaves, within which is developed the second envelope, or perianth. 



P. 106. The early divisions in the antheridium of Pallavicinia and 

 Podomitrium agree exactly with those in Porella, and further investiga- 

 tion will probably show that this method of division, in the anther- 

 idium, is more common than has been supposed to be the case. 



P. 107. The spermatogenesis of Porella has been recently de- 

 scribed in detail by Woodbum (i). 



P. 112. There is a second layer of cells in the wall of the capsule 

 in Porella, which is not clearly indicated in Fig. 57. 



P. 112. The embryo of FruUania is so diiierent from that of most 

 of the Acrogynae, that Spruce (2) has removed the family Lejeuneaceae, 

 to which it belongs, from the other Acrogynae and established a special 

 order, Jubuloideae. 



P. 113. For Goebel (12), read (14). 



P. 114. For Goebel (13), read (14). 



P. 117. Evans (4) has recently made an exhaustive study of the 

 branching in the Acrog5Tiae. 



