SYNOPSIS OF ORDERS AND GKNERA. 55 



ORDER XXI. ZYOODONTEI. 



Sporangium striated ; peristome 0, single or double ; veil cu- 

 cullate, smooth. 



Genus 69. Zygodon. Sporangium apophysate; veil small, 

 oblique ; peristome 0, single, or double. 



ORDER XXII. ORTHOTRICREI. 



Sporangium mostly striated ; veil mitriform, plicate, mostly 

 pilose ; peristome variable. 



Genus 70. Orthotrichum. Sporangium striate; veil with 

 a few keel-like folds ; leaves not curled when dry. 



Genus 71. U/ota. Sporangium striate; veil with macy 

 folds ; leaves curled when dry. 



ORDER XXTII. PTYCHOMITRIEL 



Sporangium without a tapering apophysis; veil smooth, 

 furrowed, subulate ; leaf-cells punctiform, even. 



Genus 72. PtychomUrium. Sporangium slightly tapering 

 below ; veil deeply furrowed, laciniate ; peristome of sixteen 

 deeply-divided teeth. 



Genus 73. Glyphomitrium. Sporangium roundish ; veil 

 large, ventricose, plicate, laciniate ; peristome of sixteen teeth, 

 disposed in pairs. 



ORDER XXIV. GEIMMIEL 



Sporangium equal ; veil mitriform ; leaves mostly with an 

 excurrent nerve; upper leaf-cells punctiform. 



Genus 71. Racomitrium. Veil multifid below, subulate 

 and papillose above ; ring large ; peristome of sixteen bi-trifid 

 teeth, sometimes divided to the base; lower leaf-cells narrow. 



Genus 75. Grimmia. Veil mitriform or cucullate; peri- 



