IV THE JUNGERMANNIACEyE 95 



swelling of which the gemmse are loosened from their pedicels, 

 as in Mardiantia. Similar but simpler gemmze having usually 

 three cells occur in Treubia) Blasia is also characterised by 

 the presence of colonies of Nostoc within the thallus. These 

 occupy cavities in the bases of the leaves and are normally 

 always present. 



TJie HaplomitriecB 



The two genera, Haploniitriwn and Calohryum, which consti- 

 tute this family, differ from all other Hepaticse in having the 

 leaves radially arranged, and not showing the dorsiventral form 

 that characterises all the others. The plants are completely 

 destitute of rhizoids but possess a rhizome-like basal part, from 

 which the leafy axes arise. The latter have well -developed 

 leaves arranged more or less distinctly in three rows. The 

 stem grows from a tetrahedral apical cell, as in the acrogynous 

 forms, but in Haplomitrimn at least the apical cell does not 

 develop into an archegonium. The archegonia are in this 

 genus borne at the end of ordinary shoots, but in Calobryum 

 the end of the female branch becomes much broadened and the 

 numerous archegonia stand crowded together. In this case it 

 is possible that the apical cell of the stem may finally produce 

 an archegonium. Much the same difference is observable in 

 the arrangement of the antheridia. 



Classification 



Jungermanniaceae Anacrogynae. Apical cell of female axis 

 never becoming transformed into an archegonium. 



A. Anelaterese. No true elaters, but sterile cells repre- 

 senting these. Capsule cleistocarpous. Here belong 

 the three genera, TJiallocarpus, SpJicsrocarpus^ Riella. 



B. Elatereae. Capsule opening either by four valves or 

 irregularly. Elaters always developed. 



a. Gametophore always dorsiventral, either strictly thallose 

 or with more or less developed leaves. Families, — 

 Metzgerieae, Leptotheceae, Codonieae. 



b. Gametophore upright with three rows of radially 

 arranged leaves. Fam. I., Haplomitrieae. 



^ Goebel (13). 



