The Genus Tylostoma. 



This is the largest genus and the smallest individuals that belong 

 to the tribe Tylostomeae. It is spread over the earth's surface and 

 every locality has probably one or more species. The genus is more 

 common in sandy countries. All species with the exception of two or 

 three grow in the ground. Tylostoma exasperatum (and perhaps a 

 couple of others that are little known) always grow on branches of 

 logs. 



The genus can be thus described. Exoperidium of the nature of 

 a cortex, separating more or less from the upper part of the mature 

 plant, but usually remaining more or less persistent at the base of the 

 peridium. Endoperidium opening by a definite mouth (in a few species 

 by several mouths). There is a depression or "socket" at the base of 

 the peridium into which the stipe is inserted. Gleba of branched, sep- 

 tate, capillitium mixed with the spores. Stipe distinct from the peridium 

 and inserted into a "socket" at its base. 



CORTEX. We call the exoperidium of a Tylostoma a cortex. Usually it 

 is in the nature of a sand case that separates more or less according to the age 

 and exposure of the plant, but generally partially remains at the base of the 

 peridium. Sometimes it is more of a distinct membrane, the remains forming a 

 cup at the base of the peridium; often it is smooth; usually it is more or less 

 granular with adhering sand. In a few species it bears distinct warts or granules 

 (not sand) of the nature of scales, and in one species (exasperatum) these are 

 strongly developed forming spines. 



MOUTHS. Tylostomas vary more in the nature of the mouths than in any 

 other one character, and we have used this as a basis of our classification. We 

 would divide the species into sections with five distinct types of mouths. 



Tubular Mouths (Fig. 2). Many species of Tylostoma are characterized by 

 having naked, round, tubular, definite and usually slightly (sometimes strongly) 

 projecting mouths. Such mouths are often called 

 mammose. (The species Tylostoma mammosum is 

 named from the mouth character.) However, in the 

 literal signification of the term, the name could be 

 better applied to such mouths as are shown in Fig. 5. 

 Irregular Mouths (Fig. 3). In a few species the 

 mouths are naked, and usually slightly projecting, 

 and instead of being round and tubular are elongated 

 openings. The few species having this type of mouth 

 often have several mouths on the same peridium, and 

 frequently they are confluent. Species with the other 

 types of mouths never, to my knowledge, have but a 

 single central mouth. 



Torn Mouths (Fig. 4). A few species dehisce by 

 a single torn aperture, not furnished with fibrils as in 

 the following, and not definitely marked as in the pre- 

 F . 2 ceding. All (excepting one) of the species with such 



mouths that have come to my notice, are Australian. 



Fibrillose Mouths (Fig. 5). Many species have the mouth aperture sur- 

 rounded by a layer of fibrillose tissue. This layer is built up on the peridium, 

 around the mouth, and is not merely a fibrillose opening as is the following type. 

 The fibrillose layer is variously developed in different species, more strongly in 

 Tylostoma pocufatum than in any other species to my knowledge. In old speci- 

 mens this fibrillose layer is often worn away and then the mouth becomes simply 

 a round, naked opening. (See Figs. 5, 6 and 7, Plate 82.) Sometimes this 

 fibrillose layer takes from the imprint of the cortex a granular appearance as in 

 Tylostoma granulosum. 



