NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



FIG. 13. Structure of the avicularium. 

 A. Avicularium of Bugula sabatieri Calvet, 1900. (After Calvet.) 



<zr, area. 



6, beak. 



cl, partition. 



ep, epidermis. 



I, leucocytes. 



md, mandible. 



muab, mandibular abductor muscle. 



muab', basal face of the mandible, where the 

 avicularium shows the insertion of two ab- 

 ductor muscles. 



B. Exterior portion of an immersed avicularium; ar, membranous area; 6, beak; cmd, 

 mandibular cavity; md, mandible. 



C. Longitudinal section of the avicularium of Schizopodrella ( Schisoporella) linearis var. 

 hastata Hincks, 1880. (After Calvet, 1900.) 



muad, mandibular adductor muscle. 



nine, extensor muscle of the avicularium. 



muf, flexor muscle of the avicularium. 



mup, parietal muscles. 



p, peduncle. 



pa, polypidian rudiment. 



rm, mesenchymatous network (or plexus). 



s, cilia of the polypidian rudiment. 



ce, external layer of the ciliated organ. 



ci, internal layer. 



cmd, mandibular cavity. 



vry, cryptocyst (skeleton). 



ect, ectocyst. 



epa, avicularian epidermis. 



cpT>, frontal epidermis of the bryozoid. 



epf, facial epidermis. 



cph, hypostegial epithelium. 



hy, hypostege. 



md, mandible. 



muati, mandibular abductor muscle. 



muad, mandibular adductor muscle. 



pa, polypidian rudiment (=ciliated organ). 



D. Enoplostomella synthctica, new species, X 20, showing tremopores transformed into avi- 

 cularia. 



E. Section of Cellaria denitanti MacGillivray, 1887, showing the large avicularian chamber 

 and the intermediate zooecia (c). (After Waters, 1904.) 



P. Interzooecial avicularia, with pivot, of Grammella cmssimarginata Hincks, 1S81. 



G. Curved onychocellarium of Onychocella laciniosa, new species, X 20. 



H. Straight and symmetrical onychocellarium of Floridina antlqua Smitt, 1872. X 20. 



I. Reticulocellarium of Tlwlamoporella granulata Levinsen, 1909. (After Osburn, 1914.) 



J. Avicularian zooecium of Porella plamilntrt, new species, X 20. 



