EXPLANATION OF PLATE XV. 



Steganoblastus ottawaensis. 



Fig. 1. Specimen A, from the posterior interradius, showing periproctals and, 

 above them, the supposed hydropore. 

 ,, 2. Specimen B, from the posterior interradius, showing the same 

 features. 



,, 3. Specimen A, the lip of the anterior subvective groove, showing pores, 

 adradial suture, and spine-pits. For exigencies of lighting, the 

 perradius is sloped downwards from right to left. x 5 diam. 



,, 4. Specimen A, from the right anterior interradius. 



,, 5. Specimen B, adoral view ; compare Text-fig. 5. 



,, 6. Specimen A, adapical view. 



,, 7. Specimen A, adoral view; compare Text-fig. 6. 



All the figures are from photographs by Mr. H. G. Herring, and all, except 

 Fig. 3, are enlarged 3 diameters. 



The Text-figures are based on pencil drawings by Mr. G. T. Gwilliam. 



[1914 203] 



