Plate 23 



Smittina abditavicularis, new species 



Figure A: Dorsal, attached wall of several zoids. Zoid walls are sharply defined in! 

 contrast to the frontal surface as seen in figure D. Drawn to the scale at left. 



Figure B: A cross section through three zoids. Frontal wall is at top, dorsal wall at 

 bottom. Zooecial cavity shown in solid black. Middle zoid is cut through the peristomial 

 region with the interzooecial communicating pores exposed. Multiporous plate at extreme 

 left still has its four small pores intact. The peristomial lining is shinier and smoother thanj 

 rest of zooecial wall. Drawn to the scale above. 



Figure C: Enlargement of orifice region. Thin salient mural rims converge toward- 

 the clithridiate secondary orifice. Frontal wall (tremocyst) is porous, beaded, and thick.) 

 Drawn to the scale at left. 



Figure D: Small area of colon)- showing fused frontal wall of a number of zoids. Here 

 and there raised mural rims can be seen, especially about orifice. Where mural rims are 

 obliterated zooecial boundaries can be identified because marginal frontal pores are often: 

 slightly larger and more in alignment than those elsewhere. Drawn to the scale at left.i 



Figure E: A cross section through the peristome, looking down on the primary orifice, 

 shown in black, which is bordered by a small median lyrula and two broad cardelles. Be- 

 tween the lyrula and secondary orifice, in the peristomial floor, is the obliquely oriented^ 

 median oral avicularium, the exact boundaries of which are shown somewhat indefinitely, 

 Same scale as figure C. 



Figure F: Lyrula and cardelles from inner, dorsal aspect. Black area is the primary; 

 orifice. Drawn to scale at left. 



Figure G: Somewhat lateral view of peristomial canal and primary orifice (in black) 

 toward which the small lyrula and one big cardelle point. Oral avicularium diagrammatic 

 because its beak shape could not be seen too clearly. Secondary orifice to left of avicularium. 

 Same scale as figure F. 



Figure H: Primary orifice, lyrula, and cardelles. Cardelle at left damaged and incom-ii 

 plete. Same scale as figure F. 



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