252 Evans: HEPATICAE OF PUERTO RICO 
both vegetative and sexual axes. Goebel* has demonstrated the 
fact, however, that in the Lejeuneae, for example in Lejeunea 
cavifolia (Ehrh.) Lindb., the germinating spore develops into a 
minute and short-lived thalloid structure upon which the persistent 
leafy plant soon arises. He therefore looks upon Metzgeriopsis 
as a plan in which the embryonic 0 juvenile stage is long con- 
tinued. 
In his treatment of Cololejeunea Schiffner* divides the genus 
into the two subgenera Physocolea and Leptocolea, following the 
example of Spruce.t The most important differences between 
them are to be found in the perianths, the vegetative organs sharing 
many characters in common. In Physocolea the perianth is in- 
flated and usually sharply five-keeled. In Leptocolea it is strongly 
compressed, the antical surface is plane or nearly so, and the 
postical surface bears a low rounded or two-angled keel. The two 
subgenera show the same relation to each other, therefore, as the 
genera Crossotolejeunea and Prionolejeunea, and the writer suggests 
that they be considered groups of generic rank. If this is done the 
name Cololejeunea may be retained for the first group, while the 
name Leptocolea may be applied to the second group in a generic 
sense. The first species which Spruce describes under Physocolea 
is the European Lejeunea calcarea Lib.; the first species which he 
describes under Leptocolea is the Peruvian L. micrandroecia Spruce. 
L. calcarea may therefore be considered the type of Cololejeunea 
and L. micrandroecia the type of Leptocolea. 
Among the species which Spruce includes under Physocolea 
two distinct types of. lobule are represented. The first is well 
shown by C. calcarea and its allies, the second by the European 
Lejeunea microscopica Tayl., a species which finds its closest rela- 
tives in tropical and antarctic America. The first type of lobule 
is found also, with certain modifications, throughout Leptocolea. 
The fact should be emphasized, however, that in these groups as 
in other genera of the Lejeuneae the lobule is an organ which 
often fails to develop normally and that a prolonged search is 
sometimes necessary before characteristic lobules can be demon- 
strated. 
*Flora 72: 16, 17. f. 4 
+ Engler & Pecut Nat. Pflanzenfam. 13: 121. 1895. 
t Hep. Amaz. et And. 292. 1884. 
: 
‘i 
4 
oo 
‘ 
