330 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 24, 



of acutely angular imbrications are distinguisliable upon the mesial 

 fold, and traceable along the attenuated lateral wings of the cardinal 

 angles. It is impossible to state what was the nature of the hinge- 

 area and its sides, and whether parallel or not. I figure the speci- 

 men as having aa important bearing upon the determination and 

 distribution of these fusiform Spirif&rce on the Australian continent 

 and adjacent islands, as well as adjoining lands. 

 Log. Gympie goldfield. Form. Devonian. 



Spirifera ditbia. Ether. PI. XVI. fig. 6. 



Shell transversely semicircular ; hinge-line nearly as long as the 

 width of the shell ; cardinal angles gently rounded ; mesial fold 

 having many small ribs, and wide at ventral border of shell ; eight or 

 nine ribs occur on each side of the mesial fold upon the cardinal angle 

 or lateral portion of the shell. It is evident that many small ribs 

 occurred upon the mesial fold, and some of the ribs upon the lateral 

 areas bifurcated as they approached the ventral margin. 



This shell resembles some forms of Splrifera undulata ; but the ribs 

 are finer than in normal forms of that species ; the ribbed mesial 

 fold and bifurcating lateral ribs are essential points of difiference. 

 Not having any outer shell, we have no means of determining any 

 markings upon the valves; but it differs from known species of 

 Spirifera. I know of no species, either Devonian or Carboniferous, 

 to which the above shell can be referred, the rounded cardinal angles 

 and almost semicircular dorsal valve distinguishing it from every 

 known form. 



Loc. Gympie. Form. Devonian. 



Spikifeea undifeka, var. undttlata, F. Eiim. PI. XVI. figs. 3, 4, 5, 



Ref. Ehein. Uebergangsgeb. p. 70, t. 4. fig. 5 ; Dav. Monog. Brit. 

 Dev. Brach., Pal. Soc. p. 37, t. 7. figs. 11-14. 



This well-known variety of Spirifera undifera needs scarcely 

 any description here, Eomer having described it in his ' Eheinische 

 Uebergangsgeb.,' p. 70, t. 4. fig. 5, and Schlotheim having previously 

 described S. curvatus, of which our shell is a variety. Again the 

 S. undifera of Schnur, ' Dunker's Palseontographica,' vol. ii. p. 204, 

 t. 34. figs. 9, 97i, appears to be closely allied to our Queensland shell. 

 Mr. Davidson, in his ' Monograph upon the Devonian Brachiopoda,' 

 Pal. Soc. p. 37, t. 7. figs. 11-14, figures one variety, S. undulata, 

 which appears to be scarcely distinguishable from the Queensland 

 form. Comparison with Schnur's figures of S. undifera and S. undu- 

 lata, Rom., leads me to consider them varieties or modifications of the 

 same shell differentiated according to circumstances during life. 



The Queensland specimens differ little amongst themselves, all 

 having the well-marked mesial fold in the ventral valve and eight 

 or ten ribs on either side ; the hinge-line is shorter than the width 

 of the shell, and the cardinal angles are rounded. The beak in 

 dorsal valve incurved ; there are faint tracings of the concentric 

 ridges or folds; but, owing to all the specimens being casts, the 

 more delicate markings cannot be determined. The distribution of 



