64 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



than with any other described genus, approaches both 

 Gymnodinium and Spirodinium in certain characters. 

 It agrees with Gymnodinium in having the anterior part 

 of the body relatively larger (see fig. 9, e and I), that is, 

 the transverse furrow is further back than in the typical 

 Amphidinium operculatum (see fig. 10, i and I). Then 



a 



i .,, - 



t* 



" <£- , 



e __ 



/ 



? 



A 



• i 



7 



k 



1 



m 



n 



Fig. 10. Various forms of Amphidinium found on November 18th : a to 

 g encysted and immature stages ; h and i larger and shorter forms for 

 comparison ; j side view of i ; k, I and n stages of short form ; in a 

 fission stage. 



again, it suggests the genus Spirodinium in that the 

 transverse furrow is curved so as to form an approach to 

 the spiral form (fig. 9, d and fig. 10, h). On 

 November 18th, I found that while most of the 

 individuals were of the larger and more elongated 

 form (fig. 9), a few of the older, short, broad form (fig. 

 10, i and I) were present along with various encysted 

 and Gymnodinium-like forms (fig. 10, a to g), which 

 are probably younger stages in the life-history of 

 Amphidinium operculatum. The previous day (Nov. 17) 

 when no discoloration was visible on the beach, a 

 scraping of sand taken from the usual place showed under 

 the microscope a very few active Amphidinia and a few 

 Diatoms, and also some rounded stationary Amphidinia 



