Iv RHIZOCEPHALA—LIFE-HISTORY 97 
Roscott, and S. neglecta on Inachus mauritanicus at Naples. The 
antenna, by which the Cypris is fixed, penetrates the base of the 
hair; the appendages are thrown away, and a small mass of 
undifferentiated cells is passed down the antenna into the body- 
cavity of the crab. Arrived in the body-cavity it appears that 
this small mass of cells is carried about in the blood-stream 
until it reaches the spaces round the intestine in the thorax. 
Here it becomes applied to the intestine, usually at its upper 
A B 
Fic. 68.—Development of Sacculina neglecta. A, Nauplius stage, x about 70; B, Cypris 
stage, x about 70. Aj, Ay, Ist and 2nd antennae of Nauplius ; Ab, abdomen ; Ant, 
antenna of Cypris ; /, undifferentiated cells ; /, frontal horn ; G, glands of Cypris ; 
HT, tendon of Cypris ; M7, mandible ; 7’, tentacles. 
part, immediately beneath the stomach of the crab (Fie. 69), 
and from this point it proceeds to throw out roots in all 
directions, and as it grows to extend its main bulk, called the 
central tumour (c./), towards the lower part of the intestine. 
As the posterior border of the central tumour grows down 
towards the hind gut, the future organs of the adult Sacculina 
become differentiated in its substance; the mantle-cavity being 
excavated and surrounding the rudiment of the visceral mass, 
while as the central tumour grows downwards it leaves behind 
it an ever extending system of roots. When the central tumour 
in process of differentiation has reached the unpaired diverticulum 
VOL. IV H 
