ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 491 



Pyxilla and Allied Genera.* — A. Fcrti publishes the results of his 

 study of the genus Pyxilla and its allies. The first chapter is devoted 

 tn a discussion of the nature and systematic characters of Pyxilla, the 

 species of which form three distinct groups. These groups should in 

 the author's opinion take the rank of distinct genera, and he gives 

 diagnoses of cadi under the names of Pyxilla Grev., Pteroiheca Grun., 

 ami Pseudopyxilla Forth lie then groups the species genealogically 

 under their respective genera, and describes one new species of PyxiUa 

 and four of Pseudopyxilla. Finally he discusses the morphological 

 types Pyxilla, Johnsoniana Grev., and P. Gaput-avis J. Br., as well as the 

 question of analogy with the genus Hemiaulus and other Biddulphioid 

 diatoms. 



New Fossil Diatom.j — A. Forti describes a new fossil diatom 

 from the calcareous Miocene strata of Bergonzano, Aulaeodiscus mio- 

 cmicus. It belongs to the section Areolati of Rattray, and is allied to 

 A. apedicellatus Rattr., though it may be distinguished at a glance from 

 that species. It is distantly related to A. comutus and other large 

 species figured by Brun. A. miocmicus is here figured magnified 800 

 times. 



New Fresh-water Pha3ophycea.| — W. Arnoldi describes and figures 

 an interesting new alga belonging to Streblonema, which he calls 8. longi- 

 seta. It was found by him growing on the thallus of Compsopogon in a 

 bay of the N.-Donez River in South Russia. Till now only one species 

 of the genus has ever been recorded in fresh-water, and that is not even 

 a generally accepted form. The present species varies according to the 

 time of year. In the autumn it is found in the earliest stages creeping 

 over the thallus of Compsopogon and filling up the grooves of its 

 cortical layer. It bears long bristles, which consist of twenty or more 

 cells, and reach a length of 500 //., a considerable size compared with 

 the general proportions of the entire plant. The growth of the thallus 

 is apical and very irregular, depending on the course of the grooves in 

 the host-plant. In January, February, and March the appearance of 

 the plant had greatly changed, a number of upright filaments having 

 arisen from the procumbent portion, and these were all surrounded by a 

 slimy covering, which gave a grey tinge to the whole plant. By this 

 time the procumbeut filaments of Streblonema had penetrated into the 

 cells of the host-plant, even so far as the centre ; but, as no organs of 

 absorption were found on the invading filaments, the author assumes 

 that they are not really parasitic. The structure of 8. longiseta is 

 described. It possesses unilocular sporangia, and, though the author 

 thinks he observed rudiments of plurilocular sporangia, he is unable to 

 affirm that they exist. The zoospores show certain peculiarities, which 

 distinguish them from those of other Phaeophycese ; these peculiarities 

 are described, as also the germination of the zoospores. The author 

 thinks it possible that the growths, which he took to be gametangia, 

 may develop in the summer, at which time he was unable to make any 

 observations. 



* Nuov. Notar., xx. (1909) pp. 19-38 (2 pis.). t Tom cit., pp. 39-40 (1 fig.). 

 J Flora, xcix. (1909) pp. 465-72 (2 pi.). 



