1910] Nichols,— Notes on Connecticut Mosses 149 
but consist throughout of a single layer of cells. To this group belong 
E. megalosporum (Aust.) Salm. and E. serratum (Schreb.) Hampe. 
These two species are readily distinguished. In E. megalosporum 
the leaves are obscurely serrulate, and stomata are present in the 
upper, as well as in the lower, part of the capsule-wall. In E. serratum 
the leaves are strongly serrate, while the stomata are restricted to the 
base of the capsule. 
'The second group includes all species in which the leaves possess 
a midrib. The midrib, however, even when present may easily be 
overlooked, since it is very poorly defined and in most species consists 
of little more than a double layer of cells which are similar in size and 
form to the ordinary cells of the leaf. The species in this group may 
be further divided into two well defined sub-groups. In the first, 
of which E. cohaerens (Hedw.) Hampe appears to be the only North 
American representative, the leaves are ovate-lanceolate in shape and 
are smooth or nearly smooth, except on the midrib. E. cohaerens is 
the most robust of our native Ephemereae. To the second sub-group 
belong E. crassinervium (Schw.) C. Müll, E. papillosum Aust., E. 
spinulosum Schimp., E. sessile (Br. & Sch.) C. Müll., and E. hystrix 
Lindb., of which the first three have been found in Connecticut. 
These differ from E. cohacrens in their more delicate habit and 
narrower, more lanceolate leaves which are always more or less papil- 
lose on one or both surfaces. Cardot! considers E. papillosum, 
spinulosum, sessile, and hystrix simply as well marked varieties of K. 
crassinervium. But after a careful examination of a considerable 
number of specimens of the three Connecticut species the writer has 
arrived at the conclusion that these, at any rate, are worthy of specific 
rank. 
The characters which distinguish Æ. crassinervium from £. 
spinulosum are difficult to describe. Often some of the leaves of an 
E. spinulosum plant are indistinguishable from leaves of E. crassi- 
nervium, so that it is only after a careful examination of all the leaves 
of a specimen that its identity can be established. In both species 
the leaves taper gradually to the apex and are serrate, especially 
in the upper half. In typical leaves of E. erassinervium, the teeth 
are relatively short and are produced by the slight protrusion of the 
upper ends of some of the marginal cells. In E. spinulosum, on the 
1 Bull. Herb. Boissier 7:361-363, 1899. 
