VIII. 

 ON HALICYSTIS AND VALONIA, 



WHILE dredging in the Clyde Sea area, last August, with Dr. Schmitz 

 of Greifswald, we were so fortunate as to find, both on the bar at the 

 entrance to Loch Goil and in the Kyles of Bute near Inchmarnock, an Alga 

 of a generic type new to British seas. It was growing in 8-11 fathoms 

 water, attached to shells and to Lithothamnion. Our discovery was the 

 Alga at present known as Halicyslis ovalis, Aresch. (= Valonia ovalis, Ag. 

 Spec. Alg., i. p. 431, and Gastridium ovale, Lyngbye, Tent. Hydrophyt. 

 Dan., p. 72, tab. i8b), and its nearest occurrence to our shores previously 

 recorded was Molde, Norway (Areschoug), and the Faroe Islands 

 (Lyngbye). Bornet has recorded it also from Biarritz (Alg. Schousb., 



P- 50). 



H. ovalis has the appearance of a small round or oval bladder (plate 

 XIII., fig. i), of the colour of a green grape, attached to its substratum by a 

 very short, delicate, cylindrical stalk, terminating downwards in a minute 

 disk. The cavity of this relatively thick-walled stalk communicates 

 upwards directly with the interior of the bladder. There is no formation 

 of rhizoids such as are found in Valonia. 



Dr. Schmitz and I have both independently examined the minute 

 structure of this plant, and our observations are in exact agreement. He 

 has been good enough to send me in his own words an account of his 

 examination, and I have translated it for convenience sake, as follows : 

 The somewhat thick membrane of the unicellular bladder appears out- 

 wardly quite smooth, and shows none of the striation to be seen easily for 

 the most part in Valonia cells. The stratification of this membrane is 

 exceedingly fine and barely recognisable, and has no appearance of 

 exfoliation (plate XIII., fig. 4). This membrane in the living plant is 

 coated with a thin layer of protoplasm, in which very numerous small 

 chlorophyll-grains and nuclei are embedded. The great lumen is filled 



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