JMORTH A.\LKi;i( AX KAF.LY TERTIARY BRYOZOA. 



373 



Ou the morphology of the Cheilostimialn, Quarterly Journal of Microscopical Science, vol. 

 46, pi. 17. 



The classification has been the object of study of Waters in 1898, 1909, and 

 1913. 



The operculum has a projection on each side for muscular attachment: it is 

 generally thick. The aperture bears two lateral denticles or cardelles- serving as 

 a pivot for the operculum. The ovicell is always hyperstomial. 



A Hippoporma 



e 



B. Hippoponella 



C. Hippo- 

 menella 



D. Hippo- 

 diplosia 



F. Hippadenella 



G. Hippoporella 



K. Hippozeug- 

 osella 

 FIG. 113. Genera of the subfamily Hippoporae Cauu and Bassler, 1917. 



A. Hippo porina porcellana Busk, 1860. Recent. 



B. HippoponcUn liippoptis Smitt, 1SG7. Recent. 



C. Hippmnenclla mucroncUiforiirix Waters, 1898, X 25. Recent. 

 P. Hippodiplotiia pallasiana Moll, 3803, X 20. Recent. 



E. Hippozeugosella arcuata, new species, X 20. Lower Jacksonian, Jackson, Mississippi. 



F. Hippadenella margaritifera Quoy and Gaymard, 1833, X 55. Recent. 



G. Hippoporella perforata, new species. X 20, Vicksburgian of Alabama. 



The distal part of the aperture is the anter; the proximal part is the poster. 

 The cardelles separate the porta from the vanna. The porta serves for the passage 

 of the tentacles. The vanna opens the compensation sac. which becomes filled 

 during the extrusion of the polypide. We may suppose that the larger the vanna 

 !-" the larger the compensation sac must be. and that consequently the polypide 

 '>e:ir-? more tentacles and that they ore larger. 



