Certain Points in the MorpJiology of Fridlania, &c. 467 



corresponding portion of the axis — a doctrino to wliicli 

 I have always heen disposed to adhere, however tran- 

 scendental it may seem to some minds. 



In the more typical forms, the shoot exhibits a markedly 

 bilateral character, with two surfaces — a dorsal away from, 

 and a ventral towards the surface along which the plant lies. 

 The leaves are alternate, and are arranged in three longi- 

 tudinal series (corresponding to the successive segments cut 

 off from the three sides of the apical cell), of which two 

 are dorsi-lateral and the third ventral. The leaves of the 

 two dorsi-lateral series resemble each other in all respects, 

 their insertion is more or less oblique, and they are termed 

 Lateral Leaves (PI. XV. //). The leaves of the ventral 

 series are of a different configuration, their insertion is 

 more or less transverse, and they are termed Amphigasiria, 

 or Amphigastrial Leaves (PL XV. am). 



In a great number of these bilateral forms, the lateral 

 leaves exhibit a more or less marked division into two lobes, 

 which, it would appear, originate from the two cells result- 

 ing from the first division of the Initial Leaf-cell. In some 

 cases — e.f/., many species of Jungermannia — the lobes are 

 equal and similar ; but in others the upper lobe is compara- 

 tively large, while the lower one is smaller. The lower lobe 

 is usually called the Auricle. This Auricle may be flat, as in 

 Madotheca (Porella), or remarkably pouched, so as to form 

 the curious helmet-shaped body seen in Fridlania. 



In connection with the development of the lateral 

 branches of the Foliose Jungermannieae, Leitgeb has made 

 certain observations which involve questions of the great- 

 est importance as to the relation between axis and leaf; 

 and to these I would now direct your attention. To put 

 the matter shortly, Leitgeb asserts that in a considerable 

 number of these plants the lateral branch is developed from 

 the lower of the two cells into which the Initial Leaf-cell 

 subdivides ; and that, in consequence, the lateral branch 

 appears as replacing, and therefore being potentially equi- 

 valent to, the lower lobe of the lateral leaf: e.g., in Frul- 

 lania, Madotheca, Lepidozia, &c. In other cases, as in that 

 of Badula, he asserts that only the lower portion of the 

 lower half of the Initial Leaf-cell goes to form the lateral 

 branch, leaving the other portion to form an auricle. 



