NOTES ON DINOFLAOELLATES. 21 



[The descriptions have been made chiefly from the living 

 organisms, but specimens of most species have also been 

 preserved in the two following fixatives, for the particulars of 

 which I am indebted to Prof. D'Arcy W. Thompson., 



1. Cupric acetate ... 2 gms. 2. Cupric acetate... 03 gm. 



Distilled water ...600 c.c. Cuprous chloride 0*3 gm. 



Glacial acetic acid 3 c.c. Glacial acetic acid 1*0 gm. 



Glycerine ...150 c.c. Distilled water ... 75 c.c. 



Mercuric chloride 1 gm. Camphor water ... 75 c.c. 



The results obtained with these two fixatives were almost 

 identical, but, on the whole, the first caused rather less shrinkage 

 than the second. The specimens were subsequently stained 



(1) With Iron Alum Haematoxylin. 



(2) With Thionin and Eosin. 



(3) With Tolluidin Blue and Eosin. 



(4) With Mann's Methyl Blue and Eosin. 



In this way further information as regards the internal structure 

 was obtained than was possible in the living organism.] 



Descriptions of the Species and Varieties. 



Exuviella lima (Ehrbg.) Butschli. 



Prorocentrum, micans, Ehrbg. 

 Never very abundant. Odd individuals appear from time to 

 time in scrapings taken from the inner harbour. Usually 

 found together with diatoms. 



Amphidinium asymmetricum, Kofoid, var. britannicum, 

 var. nov. Very constantly present throughout the spring and 

 summer, especially from July onwards. Maximum range from 

 below the north end of the stone wall to below Dandy Hill in a 

 band about 20 yards wide at the upper limit of the damp sand. 

 (See Sketch Maps). In spring of 1921 occurred as a 

 small isolated patch below Dandy Hill, in summer as on.' 

 or more patches below the stone wall. No discolouration 

 when the sand is covered by water. 



Description. Body asymmetrically ellipsoidal, the 

 length being 1*7 transdiameters. Epicone very asymmetrical. 



