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EMBRYOLOGY OF TEREBRATULINA. 



EXPLANATION OF LETTERS ACCOMPANYING THE FIGURES. 



m, mouth. 



ce, cesopliagus. 



s, stomach. 



t, tentacles or cirri. 



a, alimentary tract. 



pi, pallial cavity. 



pv, perivisceral cavity. 



pc, peduncular cavity. 



c, cephalic segment. 



th, thoracic segment, 



p, peduncular or caudal segment. 



h, head. 



ap, anterior parietal wall and head. 



e, area of embryonic shell. 



f, fold of larger, or ventral area. 

 pr, primary cceca. 



ds, deciduous setae. 

 es, embryonic shell. 

 x, foreign particles adhering to peduncle. 



