32 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
DESCRIPTION OF SPECIES. 
Genus BAIRDIA McCoy, 1844. 
Bairdia grayi sp. liov. (PI. IY, Figs, la, b.) 
Holotype . — Carapace medium sized, short, thick, subtriangular in 
shape, smooth, valves unequal in size. Dorsal margin strongly arched, 
ventral outline gently curved. Anterior beak, broad, rounded ; 
posterior beak blunt. Both anterior and posterior beaks slightly above 
middle height of valve. Hinge line deeply depressed, short. Right valve 
smaller than left. Overlap of valve is pronounced, especially along 
dorsal line. Length, 1-67 mm.; height, 1-21 mm.; thickness, 0-76 mm. 
Observations. — Bairdia grayi does not resemble any of the described 
forms from the Pennsylvanian and Permain of America, from which 
many species of the genus have been figured. Its blunt posterior beak 
and rounded anterior end, together with the strongly arched dorsal 
margin, are distinctive characteristics. The species has been named 
after Dr. K. Washington Gray of the Australasian Petroleum Company, 
who collected the material during his investigations in the Springsure- 
Rolleston area in Queensland. 
Occurrence . — Holotype (Comm. Pal. Coll. No. 261) : Cattle Creek, 
14 miles S.E. of Springsure, Queensland, in rich shelly limestone in 
north bank of Creek (Lower Bowen Series). 
Bairdia nyei sp. nov. (PI. IY, Fig. 2a, b.) 
Holotype . — Carapace medium sized, gently tapering from central 
portion of dorsal view. Anterior beak, narrow, almost at middle height 
of valve; posterior beak, low and bluntly acuminate. Dorsal and 
ventral margins almost straight and parallel in median portion. Post- 
dorsal margin short, steep ; anterior dorsal angulate. Hinge slightly 
depressed. Muscle scars deeply impressed, arranged in rosette in centre 
of valve towards ventral margin. Length, 1-3 mm. ; height, 0-8 mm. ; 
thickness, 0-75 mm. 
Observations. — Bairdia nyei resembles in outline B. verwiebei 
Kellett from the Permian of Kansas, but the posterior beak is shorter 
and less acuminate in the present form. The carapace is represented 
by a perfect cast and is stained reddish. The mode of preservation 
has made the muscle scars prominent. The species has been named 
after Mr. P. B. Nye, Assistant Director, Mineral Resources Survey. 
Occurrence . — Holotype (Comm. Pal. Coll. No. 262) : Cranky Corner, 
Hunter River District, New South Wales (Lower Marine Series) ; also 
at Pokolbin in the same district (Lower Marine Stage). 
Genus HEALDIA Roundy, 1926. 
Healdia chapmani sp. nov. (PI. IY, Figs. 3a, b; 4, 5.) 
Holotype . — Carapace small, subtriangular, equivalved. Anterior 
end roundly curved, dorsal margin strongly convex with margin 
straight towards posterior end. Highest point of curve in . middle 
portion. Posterior end subangulate, ventral margin slightly curved 
