90 
NOTES ON BRITISH DESMIDS. 
The genus Cosmariim is one in which great care is necessary in 
the discrimination of species, but of the following we entertain no 
doubt. 
Cosmaxium pseudoconnatum, Nordst. (PI. 140, fig. h). 
Smaller than any form of Cos. connatum. In size it agrees 
completely with Nordstedt’s measurements. It was only recorded 
previously in Ireland. 
Cosmaxium pseudonitidulum, Nordst. 
Not previously recorded in the British Isles. 
Cosmaxium tetxachondxum, Lund. 
Only found previously in Ireland. 
Cosmaxium cyclicum, Lund. 
Of which varieties have been recorded in Scotland and Ireland. 
Cosmaxium vaxiolatum, Lund. 
Recorded in Ireland only, but not uncommon at Capel.Curig. 
Cosmaxium Nymannianum, Grunoxo. 
Previously recorded in Ireland. 
Cosmaxium txuncatellum, Perty. 
A minute species only found hitherto in Ireland. 
Cosmaxium Kolmiense, Lund. 
Not before recorded, except in Ireland, but now found in 
England, as well as North Wales. 
Cosmaxium quadxum, Lund. 
The quincunx arrangement of the nodules is one feature in 
which this species differs from C. conspersum. Not previously 
recorded in the British Islands. 
Cosmaxium galexitum, Nordst. 
Not previously recorded in Britain or Ireland, 
Cosmaxium oxthostichum, Lund. 
Also new to the British Islands. 
Cosmaxium sphalexotxichum, Lund. 
Another addition to the list of the British Islands. 
Cosmaxium coxonatum, Cke. d; Wills. 
Frond about as long as broad, or rather shorter ; constriction 
deep, linear; segments quadrilateral, narrowest at the base, and 
dilated upwards, very slightly convex at the ends, rough all over 
with elongated conical granules, arranged in lines (about eight at 
the end and four on each side), side view truncate at the ends ; end 
view elliptic. 
Length -OGS-’O? mm. Breadth, ‘OTd-’OS mm. Isthmus, *02 
mm. Side view, *045 mm. broad. 
This resembles (7. biretum in form, but the granules are conical 
and prominent as in C. Brehissonii. The almost truncate ends, in 
front view, have eight of these conical projections, which impart a 
coroneted appearance. In side view the ends are also truncate, 
which would be sufficient to distinguish it from closely allied 
species, and the regular elliptic ends separate it distinctly from 
