Bibliographical Notices. 439 



object for the general excellence of an object-glass ; also of the 

 obsen-er^s management of the microscope, for the correction 

 must be accurately adjusted, and the filaments must he flat upon 

 the shde, otherwise the tme structure cannot be made out. I 

 shall detail some further particulars in regard to this beautiful 

 and interesting object, in my fortficoming work " On the Micro- 

 scope as a means of investigation." 



1. Didymohelix ferruginea, magnified 220 diameters. 



2. The filaments seen when lying sideways, or the adjustment and cor- 

 rection not perfect : 700 diameters. 



3. The filaments Ijing flat (800 diameters), and the uncoiled fibres quite 

 distinct. 



4. The filaments separated by maceration. 



This organism differs in structure from all others known, and 

 cannot be retained in Kiitzing's genus Gloeotila. We therefore 

 propose the name Didymohelix, to designate the genus in which 

 it must be placed. 



9 St. John's Square. 



BIBLIOGRAPHICAL NOTICES. 



The Botany of the Uastem Borders, with the popular names and 

 uses of the Plants, and of the customs and beliefs which have been 

 associated with them. By G. Johnston, M.D. &c. 8to. London, 

 1853. 



We have allowed too long a time to pass since the publication of this 

 very nice book without directing attention to it. Although it is 

 called Vol. I. of a work entitled " The Natural History of the Eastern 

 Borders," it is complete in itself as a Flora of that district, and is 

 pro\nded with a separate title-page accordingly. It will be remem- 

 bered that some years since Dr. Johnston published an account of 

 the plants of that part of England and Scotland, under the title of 

 " A Flora of Berwick-upon-Tweed," and, as he has continued since 

 that time to add to the amount of his knowledge of the native vege- 

 tation of his neighbourhood, the present Flora is the result of very 

 long and extended research. But the book is far from being merely 

 a catalogue of plants, for in addition to a full statement of the loca- 



