Evans: HeEpATICAE OF PuERTO Rico 221 
late. A careful comparison of the types of these two species 
shows, however, that they are not distinct and that the differential 
characters upon which Spruce relied are not apparent. In all 
probability he based his decision on Gottsche’s description alone 
and had no opportunity of consulting the type-specimens. The 
leaf-cells of LZ. valcanica are described as being destitute of tri- 
gones, but these are represented in the published figure and the 
type-specimen shows them almost everywhere. They are smaller 
than is usual in the species but vary markedly in size even on the 
same plant and are sometimes fully as large as in the typical 
material of the species. 
Among the Puerto Rico species of Prionolejeunea, the closest 
ally of P. aemula is perhaps P. acguitexta, the two species agree- 
ing in their general appearance, in their autoicous inflorescence 
and in their lack of subfloral innovations. P. aemula, however, is 
clearly distinct in the very abrupt dilation of its leaf-lobes, in its more 
sharply denticulate leaves, bracts and bracteoles, in its smaller un- 
derleaves with variable margins, and in its nearly beakless perianth. 
Another close ally is Lejeunea serrulata Mont., of Cuba.* This 
Species is still known from the original specimens only, which are 
destitute of perianths. It is dioicous, and the female branch, 
although usually simple, sometimes innovates. The species is fur- 
ther remarkable for its distinctly crenulate underleaves, the teeth 
being found along the inside of the sinus as well as elsewhere. 
The leaf-margins of ZL. serrulata are very much as in P. aeguitexta. 
Prionolejeunea Helleri sp. nov. 
Dull yellowish green, becoming brownish upon drying, loosely 
and intricately caespitose : stems 0.09 mm. in diameter, prostrate 
and loosely adherent to the substratum, sparingly branched, the 
branches obliquely to widely spreading: leaves contiguous or 
slightly imbricated, the lobe obliquely spreading, plane or some- 
what convex, more or less falcate, 0.4 mm. long, 0.35 mm. wide, 
outer part broadly ovate to orbicular, dilated from a narrow basal 
region, antical margin straight or slightly incurved near base, then 
Strongly outwardly curved to apex, postical margin aise more or 
less outwardly curved, forming a rather blunt angle, go” or more, 
with the keel in well-developed leaves, apex broad but usually 
abr uptly apiculate, whole margin (except close to the antical base) 
* Ramon de la Sagra, Hist. phys. pol. et natur. de Cuba, 9: 479. pl. 18. f. 3. 
1845. ; 
