154 



Observations. — The general shape of W. MacLeani is that of 

 W. Qaribaldiana, but its outline is uot ho angular, it is more 

 convex, the plications shorter and stouter, and it wants the 

 angular folds of the peduncular valve and the depressed 

 angular front ; the foramen is, moreover, very much larger, 

 and the beak more voluminous. Young shells of these two 

 species are very distinct from one another. 



The alliance of W. MacLeani is rather with W. (jrandis, 

 though strikingly different in shape. Young shells of these 

 species at the same stage of growth show the following distinc- 

 tive characters : — 



W. MacLeani. W. grandis. 



Rounded front Narrowed front 



no fold mesial folds 



margin in one plane margin flexuous 



larger foramen. smaller foramen. 



The species is named after my friend D. MacLean, Esq., J. P., 

 •who has rendered great service in the cause of South Australian 

 palaeontology, particularly by the bringing to light under 

 great difficulties the cranium of a balamoid whale imbedded in 

 the Eiver Murray Cliffs at Murbko, fifteen miles north of 

 Blanchetown. 



• Locality and Horizon. — W. MacLeani is profusely abundant 

 in a chalky limestone, which commences the limestone and 

 shell beds forming the Upper Murravian series at Blanchetown 

 and northward for about 18 miles. Many of the fossils in this 

 stratum, at a point about three-quarters of a mile south from 

 Mr. MacLean' s residence, Glenforslan, are pseudomorphs after 

 selenite, but in the case of the "Waldheimias their tests are of 

 the original substance, though their interiors are for the most 

 filled with gypsum. By breaking the shell away there may be 

 obtained most beautiful casts enclosing the loop, the opacity 

 of which makes it a well-defined object as seen through the 

 transparent gypsum. 



Waldheimia Vincentiana, spec. nov. Plate x., figs, l and 8. 



Shell elongated, oval, much longer than wide, greatest 

 breadth in the middle, whence the shell tapers gradually to- 

 wards the front and beak ; marked with inequidistant concen- 

 tric lines of growth. Test thick, densely punctated. 



Valves nearly equally convex ; the brachial valve most convex 

 in the umbonal region. Lateral margin of the valves nearly 

 straight, front margin slightly bisinuated. 



Beak short, prolonged, and transversely truncated by a 

 circular foramen of large dimensions. Deltidial pieces dis- 

 tinct, rather small and narrow, beaks moderately well defined. 



