NORTH AMERICAN lATER TEETIABY AND QUATERNARY BRYOZOA. 



185 



corner. C. Details of the aperture. (After D'Orbigny, 1852.) D. Portion of a recent zoarium, X 20, 

 with several ovicelled zooecia. The operculum closes the apertiu-e. E. Extremity of a zoarium. 

 F. Transverse section. (E, F, after Manzoni, 1877.) G. Operculum, X 85. (After Waters, 1878.) 



H-J. Mynozoum coarctatum Sans, 1850. H. Transverse section. (After Smitt, 1868.) I. Oper- 

 culum, X 85. J. Mandible, X 85. 



K-0. Myriozoum subgradle D'Orbigny, 1852. K. Portion of a zoarium with avicularia, X 25. 

 L. Section of tissue, X 25, Rowing the pol>-pide8 in position, the covering integument (a=ectocyst) 

 over the inner one (6); also the long pore tubes which in various places have a disk separating the con- 

 tents on the two sides of the disk. The oral diaphragm is seen as withdrawn. M. Section through 

 pol^^pide, X 85, showing: dm, the diaphragm; op, the operculum, T\-ith dotted lines to show the position 

 when partly open; d, disks in the pore tubes. N. Covering integument (a), X 85. O. End of pore 

 tube, X 500, showing the covering integument (a) and the inner one (J). It contains some cellules of 

 mesenchymatous tissue; P. Operculum X 85; Q. Mandible, X 50. (1-2 after Waters, 1900.) 



Family MYRIOZOIDAE Smitt, 1868. 



The frontal is thick and bears a tremocyst with tubules. Uniporous septulae 

 or dietellae are present. The aricularia are adventitious and bear a pivot. The 

 ovicell is hyperstomial not adjacent to the zooecium and lodged in a nichelike 

 depression of the distal zooecium. 



According to Levinsen the genera of this family are as follows: 



Easwellia Busk, 1884 (referred to the Galeopsidae by us). 



Gephyrophora Busk, 1884 (Galeopsidae). 



Myriozoella Levinsen, 1909. 



Myriozoum Donati, 1750. 



Fio. 35. — Genus Myriozoella Levinsen, 1909. 



A-G. Myriozoella Crustacea Smitt, 1868. A. Zooecia with peristomes and with cancellated frontal 

 B. Zooecia showing the ovicell. C. Zooecia without peristome, X 26.5. (A-C, after Smitt, 1868.) 

 D. Zooecia, X 26.5, much calcified, in which the frontal is not cancellated. E. Ancestrula and ances- 

 trular zooecia, X 60. F. Operculum, X 85. G. Mandible, X 260. (E-G, after Waters, 1900.) 

 12184— 23— Bull. 125 13 



