183 



ends, acutely rounded in front, bluntly rounded behind. The 

 post-dorsal area is very precipitous and concave behind the 

 umbo. The surface is ornamented with concentric lira?, which 

 are angular on the medial and anterior areas, and there crossed 

 by radiating threads, which are subspinose at the intersections, 

 the insterstitial spaces are concentrically striated ; on the pos- 

 terior half of the valve the concentric lira? are rounded, sharply 

 bent forward on crossing the umbonal ridge, and the surface 

 is granulated. 



The single dorsal plate is narrowly oblong, rounded at the 

 front, the very short posterior side is bent down at right 

 angles, roundly truncated and medially insinuated at the end. 

 The anterior portion of the plate has a wide, shallow median 

 depression, bounded by an obtuse ridge on each radiating from 

 the umbo, the whole crossed by closely-set sharply-arched 

 lamella? ; the narrow lanceolate depressed marginal areas ex- 

 terior to the umbonal ridges are granulated. 



Dimensions. — Antero-posterior diameter, 42 ; umbo-ventral 

 diameter, 12 ; sectional diameter of one valve, 6 millimetres. 



Locality. — Upper beds at Muddy Creek. 



Jouannetia cuneata, spec. nov. Plate xvii., fig. 2. 



Subglobose, inequilateral ; posterior side somewhat depressed, 

 cuneiform, its extremity bluntly rounded (not at all pointed) ; 

 the anterior side is inflated, and its extremity is rounded. The 

 shell is inequivalve by reason of the callous development from 

 the one valve overlapping the anterior portion of the other. 



An angular depression radiates from the middle of the umbo 

 with a slight posterior inclination to the ventral margin. 



The whole surface of the valve is ornamented with thin, dis- 

 tant concentric lamella?, striated in the interspaces, and distant 

 radial threads on the umbonal area of the anterior side, and a 

 few riblets towards the anterior margin and on the post- 

 umbonal ridge. 



Dimensions. — Antero-posterior diameter, 24 ; umbo-ventral 

 diameter, 17 ; sectional diameter of both valves, 16 milli- 

 metres. 



Locality. — Glauconitic sand bed in the Adelaide bore. 



The species is distinguished by its blunt posterior extremity 

 and the fewness of the lamella? of growth. 



FAMILY TEREDINID^E. 

 Teredo (Kuphus) Heaphyi, Zittel. 

 Reference. — Teredo LLeapliyi, Zittel, Pal. von Neu-Seeland, 



p. 45. tab. 14, fig. 4. 



