MUSCI. 3* 



16. Didymodon. Peristome of 16 or 32 teeth, approaching 

 in pairs or united at the base. Calyptra dimidiate. 



17. Trichostomum. Peristome of 16, equal teeth, divided 

 to the base, or 32 placed together in pairs. Calyptra mitri- 

 form. 



18. Glyphomitrion. Capsule destitute of apophysis. Peris- 

 tome of 16 teeth, approximated in pairs, reflexed when dry. 

 Calyptra covering the whole capsule, entire or rarely cleft on 

 one side and laciniated. 



19. Dicranum. Peristome of 16, bifid, equidistant teeth. 

 Calyptra dimidiate, not fringed at the base. (In some species 

 of the first division the seta is lateral.) 



20. Tortula. Peristome of 32, spirally twisted teeth, more 

 or less united at their base into a tubiform membrane. 



21. Cinclidotus. Peristome of 32, filiform, at length twisted 

 teeth, anastomosing at their base. 



22. Polytrichum. Peristome of 32 or 64 equidistant teeth, 

 united at the extremity by a horizontal membrane. Calyptra 

 dimidiate, very small. 



(See Entosthodon and Orthotrichum in Diploperistomi.) 

 Div. II. Peristome double. Diploperistomi. 



A. Internal peristome composed of distinct teeth or cilia, (in 

 Entosthodon obsolete.) 



23. Entosthodon. Peristome double (?) ; the outer of 16 re- 

 mote (horizontal and slightly oblique) teeth, from within the 

 mouth of the capsule ; inner obsolete or wanting. Capsule with 

 an apophysis. 



24. Funaria. Peristome oblique; the outer of \6, compact 

 teeth; the inner of as many cilia opposite to the teeth of the 

 outer. Capsule pyriform, its mouth oblique. 



25. Zygodon. Outer peristome of 16 teeth, approaching in 

 pairs J the inner of 8 or 16 horizontal cilia. Calyptra dimidiate. 



•2(). Ohtiiotkk him. Outer peristoma of 16 teeth, approach' 

 ' ing in pairs; the inner of 8 or 16 horizontal cilia, (sometimes 

 wanting), Calyptra mitrifonn. Bulcate. 



B. Inner peristome formed of a membrane more or lest divided into 

 liHutia or segments* 



4 



27, Him m. Outer peristome of 16 teeth; lacinia of tin- 

 inner hi, equal, frequently with filiform processes placed between 

 them. Calyptra dimidiate, 



