242 



ME. W. MITTEN ON NEW SPECIES OF METZGEEIA. 



all previously known. To the unassisted eye they scarce offer 

 more than small stems of M. furcafa, with which they agree in 

 substance and colour ; and it is only when their apparently sinuose 

 outline is detected that any difference is obvious. When, however, 

 the fronds are examined with sufl&cient power on the under or 

 ventral side, it Is seen that they have really marginal inflated 

 lobules not very different from those usual in the genus Frullania. 

 This appearance Is In part produced by the incurvation of the 

 inflated sac, so that its opening, which Is towards the costa. 



Fig. L 



A 



M, saccafa, 

 side. ( 



, natural size. B, much enlarged, showing the under or ventral 

 sac bent back in plane with the frond. D, transverse section of 

 how the many-celled costa. 



