I 



Plate 18 



Cellarinella laytoni, new species 

 (For explanation of abbreviations see key for plate 12. All figures drawn with aid of camera lucida) 



Figure A: Part of an internode. Bottom zoid is without an ovicell, but the five zoidli 

 above it show ovicells. Zoids open on all faces of the sprig. Suboral region, with its tw(v 

 mucros, juts out prominently in this species. Degree of calcification is medium. Scale i: 

 of plate 12. 



Figure B: Young, incompletely calcified zoids from tip of a branched colony. Tht 

 smooth frontal olocyst is encroached upon by the secondary, ridged, porous layer (tremocystf 

 in the areolar pore region. The strong ribs between the areolar pores, so prominent in th'Fi 

 bottom right zoid, become overgrown and indistinguishable with further calcification' 

 The typical prowlike suboral bulge is a key character of this species and shows well oi 

 lower right zoid. Scale a. 



Figure C: Top view of primary orifice of a young zoid near the growing tip of the colmn 

 Beak and mandible of internal avicularium show better here than in figure D, but th 

 external avicularial mandible is dried and a bit twisted out of position here so is not typical.i 

 Scale e of plate 12. 



Figure D: Another young zoid. Avicularial mandible inside orifice is shown from iln 

 side; it was heavily stippled to distinguish it. Base of external avicularium straddles ih' 

 midline. Scale e of plate 12. 



Figure E: Top end view of a sprig, showing two tiers of zooecia. Areolar pores ar- 

 visible on the sprawling zoid at left. Scale a of plate 12. 



Figure F: Part of a sprig which had a "node" and a chitinous rootlet. Scale aoi plate 121' 



Figure G: Base of a fragment with broken-ofi" radicle fiber or rootlet; above that a zoii 

 with two external avicularia, an uncommon condition. Scale a of plate 12. 



Figure H: Mandible of an external avicularium Scale b. 



Figure I: Mandible of an internal avicularium. Scale b. 



\ 



