

Plate 19 



Umbonula dentala (Waters) 



Figure A: Avicularium from side of orifice. Hemispherical mandible is lightly stippled 

 and posterior membranous area is blacked in hea\'ily. Drawn to the 0.1 mm. scale above/- 



Figure B: Orifice of four zoids, one of them ovicelled. Ovicell incomplete, immaturef' 

 Bifid denticle and the pair of avicularia at orifice corners are the species' characteristics: 

 Drawn to the 0.1 mm. scale at upper right. 



Figure C: A damaged or incomplete frontal avicularium, with mandible deepU' immersed,'i 

 distal to the zooecial orifice, on the next zoid. Same scale as figure B. 



