402 BOTANICAL GAZETTE [November 



emphasizes in particular S. sinuata, S. subsimplex, and S. rhizoloba. 

 He discusses the thallus, including the central strands of smaller 

 cells, the apical cell, and the branches on the ventral side of the 

 thallus. He passes over briefly the sex organs, giving no figures of 

 the antheridia and few of the archegonia. He illustrates a close 

 series of stages of the young sporophyte, but states that the later 

 details in the development of the sporogenous tissue into spore 

 mother cells and elaters remained dark to him. The only observa- 

 tions which he makes concerning the older sporophyte are that the 

 apex of the sporophyte undergoes secondary divisions, to which 

 is due the beaklike form of the tip of the capsule; that the differ- 

 entiation into elaters and mother cells occurs relatively late; that 

 the former are arranged in a direction parallel to the embryo axis 

 and that they are uniformly distributed throughout the capsule. 

 Tansley and Chick (34) discuss more fully the structure of the 

 central strand of the thallus. No other papers bearing directly on 

 the morphology of the genus have been published, and only occa- 

 sional references in connection with other liverworts have been 

 made. 



The highly developed conducting tissue of the gametophyte and 

 the mosslike development of the sporophyte make the genus pecul- 

 iarly interesting. It was hoped that a complete life history of the 

 species might be secured, but many stages are lacking. While 

 little is added to Leitgeb's account, a few facts concerning a genus 

 about which so little is known may be of interest. 



Material 



material was collected in the vicinity of Xalap 

 by Dr. W. T. G. Land and Dr. Charles 1 



Land in the autumn 



em 



of 1 910. It was killed in the field in 6 per a 



up with 50 per cent alcohol. Excepting for th 



this killing agent was found to be satisfactory 



almost a necessary one when _ 



considered. From the alcohol-formalin solution the material 



was transferred to 50 per cent alcohol, and the process of dehydra- 



time 



.-> 



x> 



