BY \V. X. BENSOX, \V. S. DUX', AX'l) W. R. BIJOWXE. 



345 



term (<(). in wliit-h the radial ridges are very marked and extend only abnut a 

 <|uarter of the way from the beak to the margin. Figures 4 and 5 illustrate (b), 

 a form that is rather crushed so that the curved outline is fractured. The radial 

 and transverse ridging is not so deeply marked, but the sinus is more noticeable. 

 It has a heavier, coarser ornamentation than the majority of the examples of this 

 sjiecies from the Burindi Beds. The shell (c ) in Figures (> and 7, is smaller than 

 the other foims, and the outline of the pedicle valve seen in profile is more 

 acutely elliptical than usual. The well-marked concentric ridging covers more 

 than a third of the surface of the valves. The i-adial ridges, however, are not so 

 continuous as usual. The fourth specimen, Text -fig. 10, is distinguished from the 

 other forms by its greater breadth relative to the length, by the presence of prom- 

 inent ears, by the even convexity of the pedicle valve and by the fact that the 

 reticulate area covers almost half the shell. The dimensions of these four shells 

 are as follow : — 



abed 



Breadth in millimetres 30 30 17 24 



Length of hinge line 27 34 15 23 



Distance from beak to margin .... 23 — — 17 



Convexity of pedicle valve 10 — 11 9 



This form was collected by Porter near CaiTolI; by Mrs. Scott and Benson in 

 the south-east of Babbinboon. 



According to Davidson (31), it extends through the Calciferous Sandstone of 

 Scotland into the Upper Limestone, and is also found in the Millstone Grit of 



Text-fig. 11 . .- Prod mi us 

 seinireticu/aliis. Bab- 

 binboon. 



Text-fig. 12. — Dielasma 

 saitnluiii var. amyg- 

 dala (Dana). Soiner- 

 ton. 



the Welsh Border. Freeh (32) states that it occurs in the lower portion of the 

 Visean in France and Belgium, and in Russia, and in America it is found through- 

 out the Tpjier and Lower Carboniferous Formations (33) . 



Ortiiis (Sciiizophori.4) kesupinata (Martin). (Plate xix., figs. 1(1, IL) 



Anomitea resupinata, Martin, Petrif. Derb., 180i;, p. 12, t. 49, f. 13-14; Schi-'o- 

 plioria resupinata, Dun, Rec. Geol. Surv. N.S.W., vii., 1902, p. 78, t. 21, 

 f. 3-9 and Bibliography there cited. 



This widely distributed form has been obtained from most of the knowa 

 fossiliferous localities in the Somerton District, and was also found by Benson 

 four miles east of Currabubula. None of the forms are well preserved, but those 

 here figured conform in all essentials to the diagnosis of the species. In both, the 

 margin forms a smooth curve, but the sinus is rather marked in one, while in the 



