2(52 KANSAS ACADEMY OF SCIENCE. 



The operculum is forced off the capsule either by the shrinking of the 

 annulus, or by the swelling of the spores, thus allowing their escape and dis- 

 semination. 



In two subdivisions of the division Musci the operculum is not developed. 

 Andreaea opens by the capsule splitting into four valves, allowing the eporee to 

 escape through the spaces. The other subdivision does not allow the spores to 

 escape until the capsule has decayed and broken into fragments. This subdi- 

 vision includes several genera — Ephemerum, Phascum, etc.: but the larger por- 

 tion of thetlivision Musci is furnished with a deciduous operculum. 



In regard to the operculum the mosses are divided into three groups. The first, 

 called Schistocarpi, are those splitting the capsule into four valves and having no 

 deciduous operculum. The second group, Cleistocarpi, are closed-fruited mosses, 

 those not freeing their spores until the capsule decays. The third group, Stego- 

 carpi, are mosses whose capsules have a deciduous operculum or lid, which opens 

 to free the spores when the capsule is ripe. The annulus is a ring, composed of 

 a row or several rows of cells (from one to four rows), which grows between the 

 lid and capsule. When the capsule is mature this ring of cells contracts on the 

 inner surface, thus freeing the operculum from the capsule. The annulus is 

 usually fugacious, but in some cases it is persistent, and is either simple, 

 compound, or revoluble, as in Funaria; or it may be entirely wanting. The com- 

 pound revoluble annulus of Funaria hygrometrica is especially good for studying. 

 (See plate XIV.) 



The mouth of the capsule when the lid is removed, may or may not have a 

 peristome or teeth. If the mouth is naked or without a peristome, it is termed a 

 gymnostomous moss ; but most mosses have either a single or double peristome. 

 When there are two rows of teeth it is said to have a double peristome ; if only 

 one row, a simple peristome. 



Often the teeth are long and slender, and very sensitive to moisture, curling 

 up in various ways either inward or outward when dry ; but rapidly becoming 

 erect when moistened. The simple peristome and also the outer row, when it is 

 double, grows from the inner lining membrane of the capsule. 



The number of teeth is usually constant in the same species ; but varies in 

 different species, from four to sixty-four ; the number always being a multiple 

 of four, doubling itself regularly, as four, eight, sixteen, thirty-two and sixty- 

 four. 



The teeth are of many sizes, shapes, and colors ; and vary greatly in their 

 surface and structure. They are sometimes long, slender, straight, and en,tire, 

 as in Barbula ; or lanceolate and closely articulate, or broadly triangular with 

 few articulations ; or perhaps blunt and irregular in shape. Sometimes they are 

 smooth and again they are either granular or densely papillose or lined with 

 plates, or lamellate on the inner surface. Again, they may be bordered by hyaline 

 edges, and marked down the center by divisural lines, or be split down the medial 

 line ; thus giving the paired arrangement of the teeth. Their color is usually 

 the same as the capsule ; but it is frequently different, it often being bright 

 orange, purple, yellow, or hyaline, but most commonly brownish like the capsule. 

 Some teeth consist of a single elongated cell, as in Barbula and others ; or of a 

 row of cells transversely jointed ( articulated ), called trabiculate. 



The inner peristome develops from the outer wall of the spore sac. It is 

 often a short membrane reaching but a short distance above the edge of the 

 capsule, and frequently it is a thin, plaited cone-like membrane, with cilia 

 between the segments or processes. The cilia are usually opposite the inter- 

 spaces of the outer teeth, and are from one to three in number, always being 



