. Mosses with hand-lens and microscope : a non-technical hand-book of the more common mosses of the northeastern United States. eedle-like beak on the operculumin this and many other species of mosses, notably Dicnniiiin, is a great it can be of any use so as to be favored by natural selection seemsimprobable. The only possible utility that I can imagine is that it serves to aidin dehiscence, causing the operculum to be knocked off more readily. As everycollector knows, it is rather a difficult matter to find matured capsules of theselong-beaked species in good condition and keep t
. Mosses with hand-lens and microscope : a non-technical hand-book of the more common mosses of the northeastern United States. eedle-like beak on the operculumin this and many other species of mosses, notably Dicnniiiin, is a great it can be of any use so as to be favored by natural selection seemsimprobable. The only possible utility that I can imagine is that it serves to aidin dehiscence, causing the operculum to be knocked off more readily. As everycollector knows, it is rather a difficult matter to find matured capsules of theselong-beaked species in good condition and keep them so in the herbarium. Oneyear I collected E. rusciforme on August 15 in excellent condition, but apparentlyimmature. When I collected for my North American Musci Pleurocarpi, Icollected three weeks later and most of the opercula had fallen. In x\\e Hypiiaccieat least, the capsules with long-beaked opercula are short and I am of theopinion that they are descended from ancestral forms with longer capsules andthat as the spore-producing portion has been reduced (for reasons not yet 290 MOSSES WITH HAND-LENS AND MICROSCOPE. understood), the line of dehiscence of the operculum has approached nearer tothe base of the capsule, leaving the upper portion as an undeveloped rudiment; that is, when the capsule begins toform at the lance-like stage of thesporophyte, this portion does not fillout [)ut simply remains in an undeveloped state. 1. Apical cells of branch leaves ohloiiK-rhomboidal tocircular 2 Apical cells of branch lea\es not materiallv different from the median cells stnulalum 2. Aquatic or subaquatic lusciforme Terrestrial 3 3. Seta rough hiam Seta smooth slrigmum E. hians ( Hedw.) J. t^c S. Plants in loose spread-ing mats, green to yellow-green, shming, creeping,often appearing flattened in a horizontal plane, branchleaves erect-speading, reaching by , ovate,not decurrent, obtusely acute to short-acuminate withthe apex often twisted toward the right, sharply ser-rate
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