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University of CaUfornia PuhUcations in Zoology [Vol.20 



portion somewhat tapering or narrowly rounded. The second (fig. 3) 

 is that of a shallow bell which, viewed from the anterior end ( fig. 2 ) , 

 presents a circular or nearly circular outline. Its movements in this 

 stage remind one strongly of those of a jellyfish, depending not so 

 much on its flagella as on its complicated system of myonemes (Kofoid 

 and Swezy, 19196) by means of which the surface is kept in constant 

 vibration. When in this condition its movements do not result in 



Figs. 1-3. Leidyopsis sp. 1. Figure showing typical form. The part of the 

 body posterior to the line showing width of ectoplasm is covered only by thin film 

 of ectoplasm. X 400. 2. Bell-shaped individual looked at from the anterior end. 

 3. Same individual viewed from the side. Figures 2 and 3 were drawn from 

 living specimens. X 300. 



much change of position. The edges of the bell do not remain passive 

 but push out in little exploratory movements. 



If a food particle comes in contact v,'ith the lower surface of the 

 bell it may be thrown off by the activities of the body, or it may be 

 caught by the mobile ectoplasm of that region, which seems to become 

 somewhat sticky. In the latter case the flagellate proceeds to engulf 

 the object, even if it is of considerable size. More frequently the 

 mobile edges of the bell may become attached to a food particle and 

 initiate the engulfing process. 



The first point of contact between the flagellate and the food 

 body, usually a particle of wood, may be very small (fig. 4), but it is 



