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ing to the amateur. Many of our species of the extreme South are merely 

 the northern limits of those which are comnion in the warmer regions of 

 Mexico and the West Indies, 



Lejeunea belongs to those leafy stemmed hepatics which have the bi- 

 lobed leaves, or leaves folded together so as to make a dorsal and a ventral 

 lobe. The ventral lobe in this genus is incurved, but not ligulate or saccate. 

 The lower lobe is always smaller than the upper and is usually more or less 

 inflated. It is separate from Radula in that the root hairs arise from the 

 stem or underleaves, whereas in Radula they arise from the ventral lobes 

 Also in Radula the perianth is compressed while in Lejeunea it is angular. 

 Frullania and Jubula have the ventral lobe saccate, while in For el la it is 

 ligulate. The leaves are decurrent at the folds, and, in all but two of our 

 northeastern species, underleaves are present. The perianth is free from 

 the involueral leaves oval or oblong, terete or angular, and with the mouth 

 carinate, cristate, or ciliate. Capsule globose. Spores large, tuberculate. 



Our Lejeunea are rather smaller than the other genera which we have 

 considered, except Frullania, which they greatly resemble in appearance to 

 the unaided eye. In habitat, they grow at the base of trees, upon their 

 bark, upon rotten logs, and some upon rocks. Sometimes species are mixed 

 together, or mixed with other hepatics or mosses, so that care should be 

 taken in identification. 



Key to Species. 



1. Underleaves present, undivided 2. 



Underleaves present, bifid , 3. 



Underleave absent 8, 



2. Lobule bluntly pointed at apex Archilejcunea clypeata. 



Lobule with long and slender apical tooth 



Archilejcunea Sellowiana. 



3. Lobe acute, underleaves with rounded divisions, and broad shal- 



low sinus Harpalej eunea ovata. 



Lobe rounded or obtuse, underleaves obtuse to acute divisions, 

 and narrow sinus 4. 



4. Lobe widely spreading, inflorescens autoicous 5. 



Lobe obliquely spreading to suberect, inflorescence dioicous 7. 



5. Lobes and underleaves distinctly crenulate Lej eunea patens. 



Lobes and underleaves entire or nearly so 6. 



6. Underleaves not rounded at base, perianth abruptly narrowed 



at base, Lej eunea cavifolia. 



Underleaves rounded at base, perianth gradually narrowed to- 

 ward the base .Lejeunea Americana. 



7. Underleaves longer than broad, deeply bifid, often unidentate 



on sides ., Microlej eunea lucens. 



Underleaves broad as long, bifid to middle, never unidentate on 

 sides Microlej eu7iea Ruthii. 



8. Outer surface of lobe rough from projecting cells or wart-like 



thickenings, no hyaline cells.. . . . Cololej eunea Biddlecomiac . 

 Ourter surface of lobe almost smooth, cells scantily convex, 

 hyaline cells often present at apex and along antical margin. 



Cololej eu7iea /ooria?ta. 



