t 



Plate 10 



Mawsonia membranacea Thornely and Melicerita latilaminata, new species 



(All figures except B and C drawn with aid of camera lucida) 



Figure A: Mawsonia membranacea. Six zooecia and an avicularium. Scale a. 



Figure B: Melicerita latilaminata. Free-hand sketch of a colony, showing beginning of 

 dichotomous branching and several rootlets sprouting from near base. Area between the 

 two dotted lines is shown in figure D. 



Figure C: Melicerita latilaminata, new species. Cross section diagram of a branch to 

 show its flatness and bilaminate character. 



Figure D: Melicerita latilaminata. Enlargement of approximate dotted area of colony , 

 shown in figure B. Zooecia are more or less hexagonal. Here and there are smaller pen- | 

 tagonal or hexagonal avicularia, four of which are pictured. Many zooecia have a small 

 crescent-shaped ovicell opening above the larger but similarly shaped zooecial orifice. 

 Scale h. 



Figure E: Melicerita latilaminata. Inner porous end wall of a zooecium. These porous 

 plates form distal-proximal walls of zooecia. Scale c. 



Figure F: Melicerita latilaminata. One complete zooecium and parts of three others. 

 Dotted lines show location and extent of body cavity of upper zooecium. External areola- 

 tion or pattern formed by the frontal surface of the various zooecia overlies and obscures 

 the true zooecial shape. Upper zooecium has an operculum in place over the orifice, while 

 the two lateral zooecia show the pair of orificial condyles. Small crescent-shaped ovicell 

 openings are at distal end of each zooecium. Parentheses lines appear around orifice of 

 upper zooecium. Scale d. 



Figure G: Melicerita latilaminata. Operculum, its surface faintly pebbled. Scale e. 



Figure H: Melicerita latilaminata. An avicularium with mandible in place showing 

 reinforcements of mandible; heaviest reinforcement is the encircling bar. Scale c. 



Figure I: Melicerita latilaminata. An avicularium from which mandible has been 

 removed to show shape of opening and the condyles, with which the mandible articulates. 

 Scale d. 



Figure J: Melicerita latilaminata. Basal region of colony with numerous rootlets 

 sprouting from zooecial fronts. Rootlets are considerab'y longer than shown. Colony is 

 narrowest here in basal region (compare with figure B). Scale b. 



