NORTH AMKRK'AX EARLY TERTIARY BRYOZOA. 483 



FIG. i: J .(!. Ccnus I'oi-'lln <iray, 1S4S. 



A-Q. PurcUii nrriconiix Pallas. ITiit!. A. /.oariiun. natural size. B. Zooecia with median 

 avicularia, X 20. C. Calcified zooecia. X 20. (A-C after Calvet. 19114.) I>. Opercuhnn with 

 its occlusor muscles. E-I. Different forms nf the peristomice. J. Anatomy of a zooecium. 

 ( D-.I after Milne-Ethvards, 1S3S. ) coc. caecum of the stomach; est, stomach; gt, tentacular 

 sheath; pit, pharynx; r, rectum. K. Transversal section. L. Ovicelled zooecia. M. A fossil 

 form of frequent occurrence. ( K-M after Manzoni, 1877.) X, (). Opeivulum, X rill, ami 

 avicularian mandible, X 130. (After Calvet l!MKi. I 1>. (.). Orifice, X r>o. and avicularian man- 

 dible, X 250. (After Waters, 1002. 1 



R-T. Pon-lln i>r<ii>iiuiua Smitt, 18o7. K. Itelative arrangement of the ovicell, peristomie, 

 ami median avicularium. S. Lateral view of a zooecium, X 50. an, avicularian umbo; or, 

 ovicell; pa, areolar pore; sp. lateral septula. T. Operculum, X 85, showing a special occurrence 

 of the occlusor muscles. (R-T after Nord.Lraard. 1!)05.) 



