Evans: HEpATICAE OF PurERTO RIco 555 
In spite of its undivided underleaves the systematic position of 
Cyrtolejeunea seems to be among the Lejeuneae Schizostipae rather 
than among the Holostipae, where it was placed by Stephani. It 
shows, to be sure, certain characters in common with Archilejeunea 
such as its single subfloral innovation and five-keeled perianth, but 
it is so much smaller than typical members of this genus and so 
much more delicate in texture that it would hardly be natural to 
include it among them. It possesses, moreover; a lobule of an 
entirely distinct type, and this will serve to separate it not only 
from Archilejeunea but from Harpalejeunea, Microlejeunca and 
Luosmolejeunea as well. 
The lobule in the Lejeuneae often affords characters of more 
than specific importance. Certain of these characters have long been 
recognized by writers ; others either have been overlooked or have 
not been fully appreciated, partly because the lobule is not always 
well developed, partly because it can rarely be satisfactorily studied 
without dissecting off the leaves from the stem and flattening them 
under pressure. These characters relate not only to the shape, size 
_ and degree of inflation of the lobule but also to the peculiarities of 
_ its free margin, with respect especially to the apex and the position 
of the hyaline papilla which is commonly found in the immediate 
Vicinity of the apex. Throughout the genus Drepanolejeunea, 
for example, a more or: less curved tooth, composed of a single 
projecting cell, is found at the apex of the lobule, and the hyaline 
papilla is situated at the proximal base of this tooth ina depression. 
Essentially the same type of lobule is developed in Harpalejeunea 
(1. 20, f. 9, 19), Trachyleyeunea and Leptolejeunea. The curved 
tooth in all these genera plays an important part in the formation 
of the opening into the water-sac, and, in the case of Leptolejeunca 
exocellata and its immediate allies, exhibits marked modifications 
due perhaps to the presence of the large basal ocellus in the lobe. 
In Microlejeunea the apex is tipped with a single slightly project- 
ing cell which is blunt and scarcely.or not at all curved. The 
hyaline papilla in this genus is sometimes borne on the projecting 
cell itself but commonly occupies the same position as in the other 
genera to which allusion has just been made. In Cyrtolejeunea 
the lobule bears at its apex a long and slender sharp-pointed and 
straight tooth, consisting of a single projecting cell, and the hyaline 
