278 THE JOURNAL OF BOTANY 



•author gives a lengthy account of cultures in the genera Scene- 

 de.wius, Clilorella, Pabnellococcus, and a few others. Chodat's 

 present ideas of specific distinctions are somewliat quaint, and are 

 in striking contrast to those which he expressed in 1902. In his 

 account of cultural experiments in the genus Sceneclesmus, he 

 describes numerous new "species," which appear to be based upon 

 physiological rather than morphological characters and would more 

 correctly be regarded as biologic forms. His inclusion of Tetradesmus 

 toisconsincnsis Smith within the genus Scencdesmiis is inconsistent 

 with the separation advocated for other genera, and Smith's care- 

 ful cultural work indicates that Tetradesmns possesses a morpho- 

 logical character of such importance as to warrant its generic rank. 



Coccomijxa snhelUpsoidea Acton is stated to be a species of 

 CJdamydomonas, notwithstanding the fact that this Alga has no 

 motile state except in special cultures, and that it lives exclusively 

 on damp rocks and stones, having entered into the thallus of that 

 most primitive of all Lichens, Botrydina vulgaris. 



Chodat still attaches great importance to the presence or 

 absence of pyrenoids in the chloroplasts of the lower Green Algae, 

 although there is abundant evidence that pyrenoids may appear 

 de novo in many algal chloroplasts and disappear in others. It is 

 upon the sole basis of the presence of a pyrenoid that he upholds 

 the distinction between Honnidium nud Stichococais, and between 

 CJdoreUa and PahneUococcus. The incongruity of this may be 

 realized when it is remembered that in some species of Ulothnx, 

 such as U. cequalis and U. subtilis, pyrenoids are habitually absent. 

 Moreover, Chodat has himself described species of the genus 

 Ankistrodesmus { = iniai)liidinm) botli with and without pyrenoids, 

 at the same time recognizing that they belong only to one 

 genus. 



A new genus, Monodits, is described, which appears to be very 

 closely allied to Cldorella; and a second one, Coccobotnjs, is esta- 

 blished for the algal cells obtained in cultures from certain species 

 of Vcrrucaria. Coccohotrys is placed alongside Botryococcus and 

 relegated to the Pha^ophyceae ! In the Lichens Solorina crocca 

 and S. saccata he finds a Coccomyxa — C. Solorina. 



Chodat again puts forward, with certain sliglit alterations, the 

 same system of classification as that in his work Etude critique 

 et exfcrimentale sur le j^olyinorijJiisme des AJyues (Geneve, 1909). 

 This system was reviewed in this Journal for 1910, p. 294, and tlie 

 criticisms then made require no further modification. 



The work is illustrated by two liundred and one text-figures and 

 by nine coloured plates of cultures on solid media. f . q w - • 



Catalogue of the JSIesozoic Plants in the British Museum {Nat. Hist.). 

 The Cretaceous Flora. Parti. ByM.C.STOPES. Pp.281 + xxiii. 

 Plates I. and II. Trustees of Britisli Museum. Price 12s. 

 The plant remains of the Cretaceous period possess special 

 interest, owing to the fact that during this epoch the Angiosperms 

 became for the first time an important constituent in the vegeta- 

 tion of the earth. Although the Angiospermic remains from pre- 



