424 Frederick ' Cliapriian : 



met with at " McDonald's," Muddy Creek, and other Kalimnan 

 localities, distinguished by its thin, depressed form, apiculate umbo 

 and stronger concentric striae. This might be appropriately 

 termed var. depressa, nov. 



Dimensions. — Type: Height, 20.25 mm.; length, 21 mm.; 

 depth of valve, 6 mm. ; length of hinge-line, 9.25 mm. ; height 

 of ligament pit, 1.75 mm. Smallest sample: Height, 11 mm.; 

 length, 11.5 mm. Locality of type, Beaumaris, from a bed 

 of white clay (Kalimnan), G.S.V. coll. 



Relationships. — Amongst a dozen examples of the genus 

 Limopsis from Beaumaris labelled as L. belcheri by McCoy, in 

 the National Museum collection, two are undoubtedly referable 

 to L. maccoyi, whilst the remainder, which are deeper shells of 

 a subtrigonal form and of a stout build, belong to the species 

 now described as L. heaumariensk. The dental armature is 

 strong, although the number of teeth is the same as in L. 

 maccoyi, from 15-19. Compared with L. iusolita, that species 

 rarely has more than 14. The ligament pit is long and deep as 

 in L. insolita, but the ornament is clearly that of L. macroyi. 

 This form is extremely interesting as pointing to a local 

 hybridisation of two tolerably distinct shells. 



Observations. — Professor Tate, in objecting to McCoy's identi- 

 fication of the recent Australian Limopsis with the Cape of Good 

 Hope species, L. belcheri, suggested its alliance to L. forskali, 

 Adams. 1 In subsequent lists Prof. Tate records L. forskali as 

 occurring in the Tintinarra Bore, S. Australia, in pre-Kalimnan 

 strata.2 This identification of the Kalimnan fossil was per- 

 petuated by later authors, presumably by comparison with Tate's 

 examples. In the Dennant collection in the National Museum 

 some very fine shells of the above species from the younger 

 Muddy Creek beds (Kalimnan) are labelled " Z,. forskali"; 

 whilst shells of the form now referred to as L. maccoyi, from 

 the older Muddy Creek beds (Balcombian). were labelled by the 

 late Mr. Dennant as " L. forskali, var.'' There is no doubt, 

 therefore, as to the shell ascribed by Tate to L. forskali, since 

 Mr. Dennant had carefully compared his specimens with Tate's 

 named examples. 



1 Trans. Roy. Soc. S. Aust., vol. xxi., 1897, p. 48. 



2 Ibid., vol. xxii., 1898, p. 68. 



