420 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



M. Zoariuni decalcified, seen posteriorly. X 45. N. Anterior view of a xooecinm containing 

 only a young polypide, X 115. (M, N after Jullien, 1888.) 



co, cardiac region of the stomach: ">., occlusnr muscles of the operculum ; 



caec, caecum of the stomach: >nrp, large retractor muscles of the polypide; 



corn, cornicula : ov ovary ; 



<li<; dietella ; /'/'. pharynx and esophagus; 



cst, stomach; /. parietal muscles; 



fit, tentacular sheath: i\ intestine and rectum; 



ir. irisoid; t, tentacles. 



O. Microporclla ftabcllaris Busk. 1852. Pietellae, from the basal surface. Besides the 

 basal \vall of flu> dietellae, the small triangular basal surface of the vibracular chamber is seen 

 lowest down to the riirht on the four zooecia. On some zooecia the basal surface shows a sep- 

 tula, and on others an opening corresponding with a septula in an opposite zooecium, X 40. 

 (After Levinsen, 1909.) 



P-W. Opercula of ^[icml)orcUa. M ciliatn Pallas, 170(5. X 85. Q. M. muliisi Audnuin. 

 1826, X 85. (P, Q after Waters, 18T8.) R. M. imrriixirn Waters, 1904, X 85. (After Waters, 

 1906.) S. M. tUunricataCsmn, 1903, X 85. (After Waters, 1904.) T. M. flabelligera Levinsen, 

 1909, X 85. U. M. decorata Reuss, 1847, X 100. V. .!/. iiittrninnta Krauss, 1837, X 100. W. M. 

 flabellaris Busk, 1852, X 140. (T-W after Levinsen, 1909.) 



Levinsen, in 1909, did not recognize the different genera established by authors 

 according to the form of the aperture. We have been able to adopt a number of 

 these genera, employing the principle of the great variations in the function of 

 calcification. 



Many species hitherto believed to belong to the Microporellae have been recog- 

 nized to belong in reality to the Adeonidae. 



Microporella Hincks, 1S77. Flustramorpha Busk. 1884. and Diponila Hincks. 

 1S79, are referred to this group, the general anatomy of which is illustrated in 

 figure 123. A discussion of the group will be deferred until the publication of our 

 monograph on the later Tertiary Bryozoa of North America. 



Group 5, DIVERS GENERA. 



The, genera of this section have some peculiar characters which do not permit 

 of their classification in any of the large groups cited; but they appear really to 

 belong to the same general family. The principal of these genera are: 



Ilouzcauina Pergens, 1889. 



Cyclicopora Hincks, 1884. 



Kymclla (.'ami and Bassler, 1917. 



C'yclocolposa, new genus. 



< 'ycloperiella, new genus. 



Aimulosin Jullien, 1888. 



Anarthropora Smitt. 



This last genus, devoid of ovicells, belongs perhaps to a distinct family. 



