302 ULVACE^E. 



42. HYDRURUS Ag. 



Char. Frond gelatinous, cylindrical, branched, solid, filled 

 with scattered, oviform bright green granules. 



Derivation. From vSwp, water, and ovpa, a tail. 



1. HYDRUKUS DUCLUZELII Ag. 



Plate LXXVII. Fig. 3. 

 Char. Frond very gelatinous, branched, plumose. 



Ag. Consp. Crit. Diat. p. 27. Batrachospermum Myosurus 

 Ducluz. Palmella Myosurus Lyngb., Dan. t. 68. ; Harv. 

 in Manual, p. 180. 



Hob. In alpine rivulets, on stones, &c. In the river 

 Walkam, near Tavistock : Mr. Ralfs. Meary, Devon : 

 Rev. W. S. Hore. 



" Root scutate, blackish, rather hard. Fronds clustered, 

 solid, very gelatinous, 2 6 inches long or more, 2 4 lines 

 in diameter, cylindrical, freely waving in the water, atte- 

 nuated towards the apex, branched ; branches scattered, 

 alternate, elongate, slender, beset with other more slender, 

 short ramuli. Gelatinous mass pellucid, viscid, colourless 

 under the microscope, without apparent margin, unless as 

 the granules imbedded within its substance indicate such ; 

 these are globose, green, formed in the stem and primary 

 branches, most densely set in the ramuli, especially towards 

 the margin. Colour of the recent frond brownish-olive, or 

 dark brown, in drying, green ; of the granules both recent 

 and dry, green. 



" The odour, in a recent state, is very offensive, and as 

 Lyngbye remarks, only to be submitted to by an algologist. 

 In a dry state it shrinks much, and most closely adheres to 

 paper. Having only seen this very interesting plant in a dry 

 state, I have thought it better to copy the above description 

 from Lyngbye. Our specimens, so far as they can be exa- 

 mined, well agree with his figure. The affinities of the genus 

 are doubtful. By Agardh it is now placed near Schizonema, 



