248 Bryophyten. 



Andrews, A. Le Roy, Notes on North American Sphagmirn,. 

 IV. (The Bryologist. XVI. p. 20-24. March, 1913.) 



The present instalment deals with the section Malacosphagman 

 and includes critical notes upon Sphagnum compactutn DC. and S. 

 strictum Sullivant. Maxon. 



Andrews, A. Le Roy, Sphagnaceae [o f North America]. (North 

 American Flora. XV. p. 1—31. June 14, 1913.) 

 A systematic treatment of the genus Sphagnum as represented 

 in North America. The author recognizes as specifically distinct 

 only 39 species from this area, reducing to synonymy a large number 

 which have been described in recent years. For example, 36 spe- 

 cific Synonyms are cited under S. subsecundmn Nee5. Maxon. 



Black, C. A., The morphologj^ of Riccia Frostii Austin. 

 (Ann. of Bot. XXVll. 107. p. 511-532. 2 pl. London, July 1913.) 

 The author gives an account of the structure of the thallus. the 

 development of the sexual organs, the sporophyte, sporogenesis, 

 development of the spore, the spermogenous cell, the diagonal 

 di Vision, the development of the sperm. The air-chambers of the 

 thallus originale by the upward growth of adjacent filaments sur- 

 rounding a depression at their junction; and v^hen mature they are 

 of various sizes and are separated by unilamellate plates of green 

 tissue. The plants are dioicous; and the reproductive organs are 

 not definitely grouped. In the spore mother cell the nucleus gradu- 

 ally decreases in size during the successive mitoses; no centroso- 

 mes or centrospheres w^ere found. The spore contains a very small 

 nucleus surrounded by food material, principally oil. It has 2 pro- 

 tective coverings; and later the endospore is formed. The sculptu- 

 ring of the exospore is an irregulär System of ridges. The final 

 division in spermogenous tissue is placed diagonallj^ in the cell; 

 no cell-wall was found between the resulting triangulär walls. The 

 blepharoplast arises from sharply differentiated protoplasm in an 

 angle of the cell; the blepharoplast elongates as a cord and beco- 

 mes closely applied to the transformed nucleus, and terminates in 

 a thickened end from which arise two cilia. The number of chro- 

 mosomes is eight for the gametophyte, and sixteen for the sporo- 

 phyte. An instance of an abnormal sporophyte, invaded by bacteria, 

 is described. A. Gepp. 



Britton, E. G., Archidiaceae , Bruchinceae , Ditrichaceae , Bryoxiphia- 

 ceae, SeUgeriaceae [of North America]. (North American Flora. 

 XV. p. 45— 75. June 14, 1913.) 



A systematic descriptive treatment of the North American spe- 

 cies of mosses of the 5 families mentioned. One new "combination" 

 appears: Ditiichum heteromalhim (Hedw.) E. G. Britton [Weisia he- 

 teromalla Hedw.). No new species are described. Maxon. 



Britton, E. G. and J. T. Emerson. Andreaeaceae (of North 

 America]. (North American Flora. XV. p. 35-39. June 14, 1913.) 

 A systematic treatment of the 9 species of mosses of the genus 

 Andreaea known to occur in North America. One of these (^. 

 tuvgescens Schimp.) is known only from Mexico. All the others 

 were described originallj^ from European specimens. Maxon. 



