imiTIRU UESMIDIE.E. 59 



Bamhttsina Brehissonii, Kutzing, Phijcologia Germanica, p. 140 (1845). 

 Uyalotheca bamhusina, Bre'bisson in lit. (1816). 



CwmBychan,3/;'. Borrer. Dolgelley ; Llanberris ; Tal Sam near Lampeter, 

 J. li. New Forest, Hants ; near Battle ; Ashdown Forest and Cliiltington 

 Common, Sussex, Mr. Jenner. Ireland, Mr. Andrews. Ambleside, West- 

 moreland, Mr. Sidebotham. Manchester, Mr. WiUimnson. Glen Lin, Br. 

 BicJde. Near Aberdeen ; and INIoss Hagg, Banffshire, Mr. P. Grant. 



Falaise, Brebisson. Germany, Kutzing. Rhodes Island, Baileij. 



Filaments pale green, soon becoming slightly opake, very slender, their 

 mucous sheath wanting or indistinct. In the water this species resembles 

 Hyalotheca dissiliens, but it is less slippery to the touch, and by this cha- 

 racter may often be known when unmixed with other Algse. The filaments 

 are regularly twisted and complete a turn in about 16 joints. The latter are 

 generally nearly twice as long as broad, but in some specimens their length 

 scarcely exceeds their breadth ; they are mflated, so that when the angles are 

 not seen, they resemble small barrels placed end to end, but when the angles 

 are fully displayed their appearance may he compared to the juxtaposition of 

 flower-pots by their mouths, the rims and intervals between which will represent 

 the crenate angles. The angles are bicrenate, and the crenatures being 

 minute and rounded, seem less like an interruption of the outline than in 

 D. Grevillii, but rather as if the angles were attached to the sides of the 

 joints. On account of the length of the joints, the disposition of the endochrome 

 in two portions is very distinct. The joints have not a thickened border at 

 their junction as in D. Grevillii, and the filament separates with less facility 

 into single joints. Occasionally, especially in the short-jointed variety, faint 

 longitudinal lines interrupted at the suture may, on careful examination, be per- 

 ceived, but I find them so uncertain and indistinct, even under the triplet, that I 

 consider it advisable merely to allude to their occurrence ; I have however intro- 

 duced a figure sho^^ing them as Mr. Jenner has observed them in favourable 

 specimens with his powerful achromatic instrument. Mr. Jenner, to whom 

 the credit of their discovery is due, does not find them in every specimen, and 

 regards them as affording an excellent test of the power of the microscope. He 

 informs me that they are situated upon the inner surface of the cell. The 

 transverse view is circular, with two minute opposite projections. The endo- 

 chrome, stellate as in the other species, has five or six rays. 



The conjugated state of this species I have gathered sparingly at Dolgelley. 

 We have seen that in this family D. Grevillii is the only known example which 

 has the spore formed within the cell. D. Borreri presents us with another point 

 of analogy between the Desmidiese and the Conjugatse. Most of the former 

 have the frond composed of a single cell, or the filament before conjugating be- 

 comes altogether broken up ; this isbut imperfectly the case here, as the coupling 

 cells have generally other cells remaining, attached either in an unaltered 

 state, or conjugated on their part with portions of other filaments, and thus 

 a kind of network is sometimes formed ; the coupling of the cells crossways 

 occasions a still more confused appearance and renders it exceedingly difficult 

 to trace them. The process is similar to that described under Ihjcdotheca 



