66 BOTANICAL GAZETTE [july 



ermis from beneath 



some instances, and of lm 



many others- A camera lucida drawing showing their typical 

 angement above the accessory cells (below in nature) is presented 



Thev are seen to have the normal form. The thinness 



in fig. 5. 



1m 



tion. 



of the normal form 



lopsis, in addition to the remarkable accessory cells, is further 

 indicated by the similar conditions presented by other cretaceous 



plants. A case in 

 Hollick and Jeffrey 



is furnished by Androvettia statenensts 

 . 9 is a photograph showing the general 

 of the species. The cells are very thick- 

 walled and irregular in shape. The numerous stomata lack 

 the definite arrangement characteristic of Frenelopsis. The more 



ermis 



ma 



of accessory cells around the stomata as before. In this case they 

 lack the conical projections of Frenelopsis, the opening having a 

 uniform outline. The presence of true guard cells is strikingly 



figu 



across 



irrounded by the accessory cells. Owing to 

 the good condition of preservation of this plant, the guard cells 

 are distinguishable in the majority of cases. Nevertheless, in 

 poorly preserved specimens they have often been destroyed just 

 as in Frenelopsis. Fig. 1 1 shows two stomata from which the guard 

 cells have completely disappeared, although the accessory cells 

 are present in their normal condition. 



Another cretaceous fossil possessing both true guard cells and 

 accessory cells is Brachyphyllum macrocarpum Newberry. A section 

 parallel to the surface of the leaf of this plant is shown in fig- i 2 - 

 In each of the stomata the two guard cells are seen to be sur- 

 rounded by four accessory cells. 



The evidence herein adduced from the structure of the stomata 

 of modern conifers, from the conditions presented in fossils of the 

 same geologic age, and above all from actual observations both m 

 section and surface views of Frenelopsis itself, appears to show con- 

 clusively that true guard cells are present in this genus, and that the 



