22 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



its length at the left side being about 0*15, and at the right 

 ventral region being about 0*5 -of the total body length. 

 Hypocone sack-shaped, more symmetrical than the epicone, 

 but sometimes slightly elongated posteriorly at the left side. 

 Antapex broadly rounded and often slightly notched by the 

 sulcus. Girdle ascending from the flagellar pore to its most 

 anterior point on the left side of the body and thence descending 

 in a uniform spiral to its distal most posterior part. Transverse 

 flagellum completely encircling the body. Sulcus extending 

 from the girdle to the posterior end of the hypocone, its left 

 border forming a flap which overlaps slightly its right margin. 

 Longitudinal flagellum extending posteriorly beyond the 

 antapex for a distance equal to the whole length of the body. 

 Nucleus situated about the centre of the body in an area 

 of clear protoplasm and surrounded by a granular radiating 

 chromatophore of a uniform yellow ochre colour. Length 150^. 



This description differs from Kofoid's description of 

 A. asymmetricum as occurring in California in the following 

 points : his specimens are only 50 ^ in length, the dorsoventral 

 and transdiameters are subequal, the course of the girdle is less 

 markedly asymmetrical than in the British form, and the 

 surface is covered with longitudinal striations. It has, 

 therefore, been thought best to place the form occurring at Port 

 Erin in a new variety of the old species. 



Amphidinium asymmetricum, Kofoid, var. compactum, 

 var. nov. Differs from the above in being more compact, 

 slightly darker in colour and usually smaller. Girdle and 

 sulcus less evident, girdle not such a steep spiral and sulcus 

 situated to the right of the mid- ventral line. Maximum range 

 of this variety roughly coincides with that of A. kofoidi (see 

 Sketch Map 2), but it is less abundant and rarely found except 

 in the outer harbour. Remains on the surface at all states of 

 the tide. 



Amphidinium eludens, sp. nov. The only dinoflagellate 

 causing discolouration on the north end of the beach. Occurred 



