ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 503 



Bryophytes of South Aberdeen.* — W. E. Nicholson gives the re- 

 sults of a collecting tour made with H. H. Knight in the neighbourhood 

 of Braemar during July, 1912, comprising 81 mosses and 82 hepatics. 

 Two hepatics new to the British flora were discovered ; and of one of 

 these — DipJopJiyllnm gijmnostomnpldlum Kaal. — a detailed description is 

 given : and botli this species and MarsupeUa apiculata Schiffn. are figured. 

 Sundry other rarities are recorded ; and some critical notes are added. 



Thallophyta. 

 Algae. 



(By Mrs. E. S. Gepp.) 



Flagellata and Primitive Algss.f — F. Cavers continues his survey 

 of recent work on the Flagellata and Primitive Alga:'. He finishes 

 Chapter 7 by showing that the simpler Cryptomonads point to the 

 descent of several divergent lines, for example, to Cyanomonas, Rhodo- 

 motias, Nephrosehnis, probably also the Dinoflagellata and the Diato- 

 maceae, and by a series of transitions to the Ectocarpaceee. The inter- 

 relationships are set out in Table C. 



8. Peridiniales (Dinoflagellata) and their relationships. These are 

 mainly marine, are unicellular, have two dissimilar flagella — one longi- 

 tudinal, one transverse— and are mostly clad with a cellulose wall of 

 sculptured plates. Schiitt divided the Peridiniales into three families — 

 Cymnodiniacese, Prorocentraceae, and Peridiniaceas. Eecent work 

 modifies this classification, and affords a basis for new phylogenetic 

 interpretations. It is suggested that the Peridiniales as a whole form 

 two distinct series which are of independent origin from the Crypto- 

 monads. The Gymnodiniace^ may have arisen from a Cryptomonad-like 

 Protochrysis, and through Diplodinium lead on to Phytodiniacese, which 

 in turn lead on to Xoctilucaceae (Cystoflagellata). The structural 

 characteristics of the various genera are discussed and figured. 



9. Conclusion. In summing up his survey, Cavers is of opinion that, 

 starting from a hypothetical autotrophic MuUiciUa-\ike ancestral form 

 (with reticulate chromatophore, numerous peripheral nuclear bodies and 

 numerous flagella) there are many lines. Several have never risen 

 beyond tlie stage of Flagellates ; and most of them have assumed a 

 heterotrophic nutrition ; but only three of them can be traced up into 

 the vegetable kingdom, and these lead respectively : (1) through the 

 Polyblepharids to the Chlamydomonads and thence to the majority of 

 the Green Alga3 ; (2) through the Chloromonads to the Confervales ; 

 (3) through the Chrysomonads to the Cryptomonads and thence to the 

 Phfeophyce^e, the Peridiniales, and probably the Diatoms. But it is 

 much more difficult to trace a connexion with the Red Algae. Possibly 

 these are of the same stock as the Dictyotace^, which stand rather 

 isolated among the Ph^eophyceag. The Cyanophyceae may be considered 

 as of kin with the Bacteria. A bibhography of 158 papers is appended. 



* Journ. Bot., li. (1913) pp. 153-60 (1 pL). 



t New Phytologist, xii. (1913) pp. 177-87, 225-32 (3 pis.). 



