ALG2E. 
103 
ing discovery of antheridia in the same genus, certainly strengthens 
the argument in favour of the alliance of the genus with the 
Bangiaceas. In a new variety of P. Mexicana , Prof. Lagerheim 
has noted in addition to the usual mode of reproduction a second 
mode in which the monostromatic frond becomes divided by 
horizontal and vertical walls into one or two layers of four- 
celled sporangia. These four-cells are freed by the dissolution of 
the mother-cell, and are motionless spores of irregular, roundish, 
rectangular or triangular form. Prof. Lagerheim has also 
observed pyrenoids in the vegetative cells of Prasiola. 
Parasites on Alges. By Geo. Murray. (“ Natural Science,” 
Yol. ii., Feb., 1893.) 
Mr. Geo. Murray contributes an interesting paper on the para- 
sites on Algse to the February part of “ Natural Science.” Be- 
ginning with animal parasites the author mentions the so-called 
“galls” on Vaucherice , first described and figured by Yaucher, in 
1803, caused by the attacks of an animal which at various times 
has been identified as Cyclops lupula, Notommata Werneckii , or 
Rotifer vulgaris. The malformations of the thallus of Rhodymenia 
palmata , caused by the copepod Harpacticus chelifer, which during 
a stage of its existence burrows in the tissues of the Rhodymenia , 
those of Desmarestia aculeata, also caused by a copepod, and those 
of Ascophyllum nodosum , caused by a nematode worm Tylenchus 
fucicola, all of which were first described by Miss Barton, are next 
dealt with. 
Passing from animal to vegetable parasites, mention is made of 
Chytridia — plants belonging to an aberrant type of fungi — several 
species of which inhabit fresh water and marine Algse. On our 
own coasts Chytridium tumefaciens is commonly to be met with on 
species of Ceramium, Ch. sphacelarum on Sphacelariae and 
Cladostephi, and Ch. plumules on Antiihamnia. Mention is made 
of papers by Braun, Bail, Cienkowski, Cohn, Magnus, King, 
Perceval Wright, Pfitzer, and Zopf dealing with this interesting 
group of fungi. 
Of Algal parasites Chlorochytrium and Phyllosiphon are alone 
mentioned. Finally mention is made of the tubercules on the 
fronds of Florideae, described by Dr. Schmitz as caused by 
Bacteria. 
The paper may be said to deal exclusively with parasites other 
than Algse, and we trust that before long Mr. Murray will give us 
a continuation, dealing with this most interesting portion of the 
subject. To go no further than our own coasts many most 
interesting parasitic Algas are not uncommon at many stations 
along our shores, for instance, Chlorochytrium immersum , inhabiting 
the fronds of Schizonemata, Ch. inclusum those of Dilsese, Ch. 
dermacotolax those of Polysiphoniae and Polyides, Cholocystis 
Cohnii those of Schizonemata and Polysiphonias, Entoderma viridis 
those of Nitophylla, Ent. Wittrockii those of Ectocarpi, and 
