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CASWELL GRAVE. 



thus differing widely from the small transparent eggs of Synapta 

 digitata. The efficient locomotor and feeding apparatuses with 

 which the larva' of the latter species is provided, enabling it to 

 care for itself, are not needed by the larva of Cucumaria doliolum 

 for whose care provision has already been made. The larva of 

 Cucumaria can, as it were, give its whole attention to the pro- 

 duction of a creature with the structure of the adult while the 

 larva of Synapta must make this secondary to food getting. 



Crinoids. 



In Antedon rosacea, the only species of crinoid the develop- 

 ment of which has been studied, the eggs are supplied with con- 

 siderable yolk and for a time the developing larvse are brooded. 



X" 



FlG. 4. Larva of Antedon rosacea. After Seeliger. Internal organs shown in 

 posterior end. I, 2, 3, 4 and 5, ciliated rings. 



The free-swimming period is of short duration and the develop- 

 ment is more or less direct. The larva is elongated and cylin- 

 drical and is encircled by five transverse ciliated rings. An 



