224 RECORDS fiF THE AUSTRALIAN MUSEUM. 



gradually rouuded. Auteiior end very small aud lobe-like, 

 the margin proceeding therefrom practically straight, rounding 

 below into the ventral ; anterior slope nearly vertical. 

 Posterior end constituting nine-tenths of the entire valve, 

 divisible into the body and wing; the former in the uiiiboual 

 region, is high, prominent, narrow above, gradually expanding 

 and becoming flattened downwards; the latter is large, flat 

 transversely, but gently convex in sections from above down- 

 wards. Umbo (defective) apparently acuminate, inclined 

 forward and projecting above the dorsal margin. Ligamental 

 area very finely grooved ; lower lateral tooth extends from just 

 posterior to the umbo half way to the posterior margin, the 

 superior commences at about half the length of the lower, 

 terminating at the same point. Adductor scar longitudinally 

 oval, situated partly on the posterior wing and partly on the 

 umbonal slope ; sculpture unknown. 



Obs. — These imperfect casts indicate a form quite new to 

 our Permo-Carboniferous fauna, and for which we have no 

 receptive genus. With one exceptional feature they accord 

 better with the characters of Hall's Glyptodesnia, although a 

 Devonian genus, than with those of any other known to me. 



Like Glyptodesma, this Bundauoon fossil is aviculo-pterini- 

 form, with a small auricular anterior end, a finely and continu- 

 ously grooved ligamental ai'ea, two oblique lateral hinge 

 teeth, a well-marked anterior adductor scar, and pallial muscle 

 insertion pits. On the other hand our specimens lack the 

 "irregular transverse plications along the cardinal margin," 

 hence a note of interrogation after the geuei'ic name. 



Genus Paracyclas, J. Hall, 1843. 



(Geol. New York, pt. iv., 4th District, 1843, p. 171). 



Ohs. Fanicycla^ has hitherto been regarded as a Devonian 



genus, but the elegant little shells (PI. xl., figs. 6 aud 7) 

 so entirely conform to the characters of many species of 

 Paracyclas, that 1 am constrained to use it for our Permo- 

 Carboniferous species rather than propose a new name for what, 

 after all, may turn out to be allied to one or other of the 

 chaotic genera of Dana, McCoy or De Koninck. 



