PLATE 15 

 (All figures by Miss Eogick.) 



Fig. 1 Stomachetosella producta, secondary calcification. 



Fig. 2 The same, diagram of a longitudinal section showing thickness of 

 frontal wall. 



Fig. 3 The same, form of primary aperture. 



Fig. 4 Posterula sarsi. 



Fig. 5 Stephanosella biaperla. 



Fig. 6 The same, detail of ooecium. 



Fig. 7 Mucronella ventricosa. 



Fig. 8 Mucronella dbyssicola. 



Fig. 9 Mucronella, the lyrulae of: 

 a. M. immersa. 

 1). M. ventricosa. 

 c. M. abyssicola. 



Fig. 10 Mucronella spinulifera. 



Fig. 11 Scruparin clavata, outline sketch showing normal and reduced fertile 

 zooecia. 



Fig. 12 Aetea ang%dna. 



Fig. 13 Electra monostachys, spinous variety, frequently all of the spines 

 except the large basal one are wanting. 



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