ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 695 



which begin life attached, change their characteristics when they become 

 free-swimming. 



Yorkshire Diatomacese.*--M. H. Stiles gives some lists of Yorkshire 

 Diatoms gathered in 190. r >. These form a supplement to R. H. Philip's 

 report in a previous number of the same journal. One of the lists is an 

 enumeration of 81 species and varieties not previously recorded for 

 Askern, among these being Philip's new variety of Frwjilaria capucina, 

 with a curious median inflation ; this is figured as var. inflata. The 

 other list comprises 64 species and varieties from a small hillside streamlet 

 at Ilkley. 



R. H. Philip t publishes notes on some Diatoms collected in the 

 district round Hull in 1904-5. In all some 13 species or varieties were 

 found which had not been previously recorded, and these are all figured. 

 Ten of them are marine, and the rest came from fresh-water. The rare 

 Stephanopyxis turrk was found again in Ascidian molluscs. The plate 

 is re-published in the " Naturalist " % with an abstract of the paper. 



R. H. Philip § gives lists of Diatoms collected in a pond in Boynton 

 Woods (18 species) and in a stream falling into Little Thornwick Bay 

 (18 species). In the lower part of this stream a marine species, 

 Coscinodiscus radiatus, is very plentiful considerably above high-water 

 mark. Only one other marine species was found. In ponds at Speeton 

 a few species of Desmidea? occur in abundance. 



Fossil Diatoms. || — A. M. Edwards records the finding of 10 species 

 of BacillariEe in the rocks of the Hudson River Epoch of the Lower 

 Silurian Age in New Jersey. All the species are identical with the 

 Bacillarise of the present day. He describes the method employed for the 

 separation of the specimens from the rocks, and shows that it is im- 

 possible for them to have become introduced during the process of 

 cleansing. They must therefore be fossil. 



Polymorphism of Cyanophyceae.f — H. Royers shows that Meyen's 

 new alga, Listia Crustacea, from the Laacher See, is synonymous with 

 Rivularia minutula Born, et Flah. It germinates from resting spores 

 which are formed at the thick end of the plant, and the filaments with 

 their false branching form a hemispheroidal green thallus, held together 

 by tough gelatinoid matter. After dissolution of this thallus the 

 individual threads become attached to submerged stones and grow in the 

 form of a Schizosiphon. They reproduce themselves by means of 

 hormogonia. They must not be confused with the Scytonema-fovms 

 which occur in the same place and are reproduced in the same manner. 

 Under certain conditions pieces of the Rivularia become converted into 

 a iVosfoc-thallus, regarded by the author as being Nostoc lichenoides 

 Vauch. In other circumstances, when associated with certain fungal 

 hyphae, the plant forms the lichen Collema pulposum var. hydrocharum 

 Ach. A bibliography and illustrations are added. 



* Naturalist, 1906, pp. 128-9 (1 fig.). 



t Trans. Hull Sci. and Field Nat. Club, 1906, pp. 217-18 (1 pi.). 

 % Naturalist, 1906, p. 67. § Tom. cit.,pp. 262-3. 



|| Nuov. Notar., xvii. (1906) pp. 174-80. 

 If Jahresb. Nat. Verein. Elberfeld, 1906, pp. 3-40 (3 pis). 



