348 Scientific Proceedings, Royal Dublin Society. 



the stomata or in the structure of the epidermis. We find, however, a 

 marked difference in the size of the stomata. Those of Sequoia are 56-64|< 

 long; those of Cryjjtomeria only iO-iQ/i in our material. If this difference 

 held good in general, it would be a useful means of discrimination. The 

 following table gives the results of measurement of the length of the 

 stomata : — 



It will be seen that the fossils referred to Sequoia agree with the living 

 species of the genus, their smallest stomata being larger than the largest ones 

 of Cryptomeria. 



The Glyptostrohus measurements seem to cast doubt on the taxonomic 

 value of the size and arrangement of the stomata. Those in the specimen 

 from South China, showing spreading yew-like foliage, lie parallel to tlie long 

 axis of the leaf, and are of the size of those of Cryptomeria in contrast to 

 those in the Hong Kong specimens, with adpressed foliage, which, though on 

 the whole parallel to the long axis, are less regularly arranged, and of a size 

 comparable to those of Sequoia. 



While in most of the species listed stomata occur on both upper and 

 under surface of the leaf, in Athrotaxis laxifolia they are confined to the 

 upper surface. The stomata on the under side of a leaf generally form two 

 bands or ribbons parallel to the midrib. In the ribbon one may see in many 

 cases distinct rows or files of stomata. When the leaf isdeeurrent the bands 

 can be traced on to the stem. These " stem '' stomatal bands are particularly 

 well marked in Glyptostrohus. In Sequoia the individual stomata lie with 

 their long axis for the most part parallel to the midrib ; in Cryptomeria they 

 are more irregularly arranged. Florin, who has investigated the epidermal 



* We are indebted to Professor A. Henry for this material. 



