Fungi, Myxomyceten, Pathologie. 359 



and very unequal in size. Conidia unknown. Species predominantly 

 aquatic. 



A. Antheridia (perhaps also oogonia) not cut off from the myce- 

 lium by septa. 



1) P. tenite, Gobi. 



B. Antheridia and oogonia cut of by septa. 



1. Oospores smooth. 



2. P. gracile , Schenk. 



3. P. monospermuni, Frings. 



4. P. indigoferae , n. sp. 



2. Oospores reticulate 



5. P. dictyospermum , Racib. 



II. Sub-genus Sphaerosporangmm. 



Sporangia spherical or oval (not filamentous) cut off from the 

 m3^celium b\' septa. 



A. Sporangia proliferous, conidia unknown. 



1. Oogonia smooth. 



P. proliferuni , de Bary. 

 P. ferax, de Bary. 



2. Oogonia spiny. P. rnegalacanthum, de Bary. 



3. Sexual Reproduction unknow. P. diacarpmn, n. sp. 



B. Sporangia not proliferous, often transformed into conidia. 



1. Oogonia and Oospores smooth. 



P. palinivorwn n. sp., P. rostratimi n. sp., P. de Baryaniim, Hesse, 

 P. vexans de Bary, P. idtimiim Trow, P. Anguüulae aceti Sadebeck, 

 P. intennediiitn de Bary. 



2. Oogonia smooth. Oospores spiny. 



P. cystosiphon, Linstedt. 



3. Oogonia spiny. Oospores smooth. 



P. artotrogiis, de Bary. 



In the 2i^<^ part of the paper the author describes a number of 

 new species of Chytridiaceae parasitic in species of Pythhim, a genus 

 in which their presence has been previously almost entirel}^ unknown. 



A füll account is also given of the life history of the group with 

 notes on the different types of Variation observed. There was no 

 indication of a sexual process in any of the species investigated. 

 The explanation given of the ripening of the sporangia differs from 

 that given by Fischer and others, but it agrees more closely with 

 Harper's accounr based on a cytological, study of Synchytrium 

 decipiens. The authors own observations are from the study ot 

 living material. 



A curious phenomenon was observed in the germination of the 

 zoospores of Pseudolpidiurn Pythii and P. aphanomyces. After the 

 disappearance of the cilia, a pseudopodic flagellum appeared at the 

 point of insertion of the front cilium. About 20 minutes later the 

 flagellum was retracted and cilia were again produced. This process 

 appears to be constant in P. Pythii. In addition to notes on various 

 species of Chytridiaceae, the following novelties are described: 



Pleolpidiuni irreguläre on Pythitim? vexa}is, P. inßatum on 

 Pythiitm interuiedium , Pseiidolpidium Pythii on Pythiuni, various 

 species, P. gracile on Pythiuni intermediuni , Nowakowskiella ramosa 

 on Triticum vulgare, Pleolpidium cucidus on Pythimn intermedium. 



A. D. Cotton (Kew). 



