2 Transactions of the Society. 



Nor does it include even all the species actually observed, but only 

 sucb as previous knowledge or the books at command enabled me 

 to identify, or such as I had reason to believe were hitherto un- 

 described forms. In particular the OscUlariaceae and Diatomaceae 

 require much more careful working out. 



The Desmidieee naturally form a considerable portion of the 

 list. During the year 1884 the most important addition to 

 the literature of this interesting class since Ealfs's ' British Des- 

 midiese' (1848) has been made, in the publication of the Eev. F. 

 Wolle's ' Desmids of the United States.' Although something has 

 been done in the interval by Archer, Cooke, Bisset, and others, 

 yet, notwithstanding the great beauty and variety of the form in 

 desmids, and the ease with which a large number of species can be 

 recognized, it is probable that more still remains to be done in this 

 group than in any other of the English flora. It is impossible to 

 praise too highly the beauty and accuracy of the drawings, as a 

 whole, in Ealfs's work. In many instances, however, my measure- 

 ments ranged somewhat larger than those of the veteran desmidio- 

 logist. 



With regard to the distribution of desmids, many species seem . 

 to be almost ubiquitous, occurring in nearly all gatherings, from 

 all altitudes. Whether other species are, like those of flowering 

 plants, limited in geographical area or in adaptability to climate, is 

 a question which has yet to be answered, and the answering of 

 which will be by no means easy. 1 have thought, however, that I 

 have noticed that the larger and more striking species are especially 

 abundant at high altitudes. Gatherings from about 1800 feet, 

 above Codale and Easedale Tarns, were especially rich in these. 



Unless otherwise stated, all the species named were observed in 

 the district of Loughrigg, Westmoreland. The gatherings were 



Fig. 18. — Stavrastrum buUosum Benn. x 400. 

 „ 19. „ „ empty frond x 400. 



„ 20. „ „ front view x 400. 



„ 21. „ teliferum Ealfs var. convexum Benn., front view X 400. 



„ 22. „ „ dividing, early stage x 400. 



„ 23. „ „ „ later stage x 400. 



„ 24. „ tuberculatum Benn. X 400. 



„ 25. „ enorme Ealfs x 400. 



„ 26. — Tetmemorus penioides 'Berm. x 200. 



„ 27. — Zygnema cruciatum Cleve, zygosperm germinating while in parent- 

 cell X 200. 

 28. — Zygnema HassalKi Benn., filament in non-conjugating condition 

 X 200. 

 „ 29. „ „ filament before conjugation x 200. 



„ 30. „ „ filaments in conjugation x 200. 



„ 31. — Mesocarpus ? neaumensis Benn. x 200. 

 „ 32. „ „ with zygosperm x 200 



„ 33. — (Edogonium macrandrum Wittr. x 'i^OO. 



