-65- 



r.Ki iRCI A. 



This genus was named after Georg-e III., but its name was 

 soon after ehanged to Tetraphis by another botanist. The latter 

 name refers to the four large strong teeth of the peristome, by 

 which character alone the genus is readily recognized. The pel- 

 lucid Georgia {G.pelliccida, Figs. 4-7) is very abundant on moist 

 decaying wood, but seems to flourish best on the vertical sides of 

 old stumps. .Some of the plants bear peculiar looking tufts of 

 leaves at the summit that might easily be mistaken for the 

 antheridial heads. The species, however, is monoicous and 

 these heads consist of large numbers of minute bright-green 

 bodies, called gemm;c, surrounded by modified leaves. These 

 bodies much magnified are shown in Fig. 7. These fall off and 

 develop into new plants This metliod of reproduction is rather 

 rare in mosses and reminds one strongly of the gemm.'c of 

 Lycopodium or the bulblets of Cystopteris. 



There is another species of this genus and another genus of 

 this family which are found in North America, but they are so 

 rare that none of our readers are likely to meet with them. 



While Georgia belongs to a different family from the hair- 

 caps, there are certain resemblances that have led| botanists to 

 put them into one group, the Nematodontete or thread-toothed 

 mosses in contrast to the Arthrodontea? or jointed-toothed mosses. 

 The jointed-toothed mosses have the teeth of the peristome 

 crossed by very conspicuous bars or joints which are forraedby the 

 thickening of the cell walls of a single layer of cells. The mosses 

 we have thus far taken up belong to the thread-toothed mosses, 

 in which the teeth are 'not jointed and are derived from several 

 concentric layers of cells. In Georgia the teeth are formed from 

 the division of the whole cellular tissue of the interior of the lid, 

 but in the Polytrichaceic the teeth are formed from more clearly 

 differentiated tissue. Each tooth consists of several layers of 

 fine threads (hence the name, thread-toothed), held together by 

 cellular material. In Dawsonia the threads are set free and 

 form brush-like tufts of cilia. These structures are so funda- 

 mentally different from those in the jointed-toothed mosses that 

 Arthrodonteic and Nematodonte;e ought to stand as the great di- 

 visions instead of Acrocarpous and Pleurocarpous. 



The Buxbaumias and their allies, the oddest and most curi- 

 ous of all our mosses, belongs with the thread-toothed mosses, ac- 

 cording to most recent writers, but they are not very common and 



