Species of Limopsis. 427 



are somewhat similar in shape to the preceding, but are smaller, 

 and rounder in outline. The shell is a,lso radially striate, 

 as in the European Oligocene specimens. In these Plio- 

 cene specimens the inner margin of the shell is smooth, in 

 this feature differing from the older, Oligocene, examples men- 

 tioned above. In this minor character it agrees with the 

 Southern Hemisphere type of shell. 



It is probable, judging from the above comparisons, that both 

 Broochi's and Sowerby's specimens were somewhat worn, since 

 typical shells of both species from type localities shoAv the radial 

 striae. Taking the evidence as a whole, there is good ground 

 for regarding the Northern and Southern types as distinct ; 

 L. aurita being a rounder form, with simple striae or radial 

 punctae, on the concentric rugae. 



The Identity of the Southern Forms of the " avrita " ti/pe 

 with L. insolita. — The most important distinctive feature be- 

 tween the Northern and Southern forms of the " aurita " type 

 of Limopsis is the nature of the radial striae. As seen in the 

 Victorian (Spring Creek) specimens, and also verified in the 

 New Zealand (Oamaru) shells, this radial striation is complex, 

 the sides of the pits producing a secondary and divergent series. 

 McCoy' refers to it as follows: — 



" Well-preserved si^ecimens show under the lens close, obtuse, 

 radiating striae, about twice their thickness apart on the flat 

 portion of the concentric laminae, each seeming to widen and 

 dichotomise towards the edge, which it does not pass (about 10 in 1 

 line at 3 lines from the V)eak)." By reference to Plate LXXXV., 

 Fig. 11, it will be at once seen that this divergent striation is due 

 to the efiect of the pitted ornament. This peculiar character of 

 the pitting is not seen in the European shell, L. aurita, which 

 has simple striae equally s])aced with the concentric rugae, 

 and consequently imparting a tesselated appearance to the shell- 

 surface. 



The Victorian, South Australian, Tasmanian, New Zealand, 

 and Patagonian specimens of this type, tested by the above and 

 the other characters mentioned, are thus seen to belong to 

 L. insolita. The originally described examples came from the 



1. Loc. supra cit., \i. 23. 



