54 HANDBOOK OF BRITISH MOSSKS. 



tinct apophysis; spore-sac undulated; veil densely pilose; 

 nerve of leaf covered with longitudinal plaits. 



Genus 62. Pogohatum. — Sporangium oval or oblong; veil 

 densely pilose ; spore-sac undulated ; leaves densely lamellate. 



Genus 63. Oligotrichum. — Sporangium subcylindrical ; veil 

 with scattered hairs or apical papillae ; spore-sac undulated. 



Genus 64. Atrichum. — Sporangium subcylindrical; veil 

 nearly naked, spinulose at the tip ; spore-sac adnate with the 

 wall of the sporangium. 



Obdeb XIX. BUXBATTM1MI. 



Sporangium oblique; peristome a conical membrane sur- 

 rounded by layers of cellular tissue, divided into irregular 

 teeth, or a rudimentary ring. 



Genus 65. Diphyscium. — Sporangium subsessile ; peristome 

 a twisted plicate membrane, surrounded by a narrow filmy 

 ring. 



Genus 66. Buxbaumia. — Sporangium large, flat above; 

 peristome a conical plicate membrane surrounded by three or 

 four layers of cellular tissue, divided into irregular teeth; 

 leaves rudimentary. 



Oedbb XX. TETRAPHIDEI. 



Sporangium straight; peristome confluent with the top of 

 the columella, which is divided into four pyramidal teeth. 



Genus 67. Tetrodontium. — Peristome of four short teeth; 

 leaves minute; lineari-clavate. 



Genus 68. Tetraphis. — Veil torn at the base; peristome 

 of four triangular-elongated teeth ; leaves normal ; leaf-cells 

 large. 



