Batesford Limestone. 809 



Among the Batesford echinoids the genus Liiitliia calls for a- 

 few remarks. Its distribution is from the Cretaceous to Recent, 

 but it is typically Miocene, and its maxinmm development was 

 attained at that period. In conformity with the recognised 

 law of increase of size in phyletic l)ranches, the genus Linthia 

 affords an interesting case in point. It probably attained its 

 largest dimensions in L. gigas, McCoy sp., from the Murray 

 Cliffs, the type specimen having a length of seven and a-half 

 inches. 1 The stratum in which it occurs is of Barwonian ag^e 

 (i.e., Balcombian or Janjukian), but presumably Janjukian. 



Of the twentv-three spp. of polyzoa recorded from Batesford 

 bv Mr. C. M. Maplestone, four species are found living — viz., 

 tSeleuaria conclnna (S. xlustralia). 'S'. marginata (S. Australia), 

 Steganoporella magnilahris (Australia, X. Zealand and Japan), 

 and Porina gracilis (Australia). Thus the ratio of living to 

 fossil forms is 17 per cent. 



The brachiopod, Rhynclionella squamosa, Hutton. is still 

 living S. of Kerguelen Island. 2 



The comparatively modern aspect of the Janjukian strata is 

 shown by the group of the ostracoda. Of the nine species 

 here recorded, one is new, whilst eight are living at the present 

 day. The distribution of these living species ranges from Ker- 

 guelen Id. to Torres Strait, the Indian Ocean and the China 

 Seas : whilst one species is found in the Atlantic. Three hare 

 been recorded from Bass Strait and two from Port Jackson. 



Although the species of sharks, represented in the Batesford 

 Limestone by teeth, are not numerous, they possess a special 

 interest. Perhaps the most important is Oxyrhina retrofiexay 

 by far the commonest form. This species is found in several 

 other localities where beds of similar age are exposed, and 

 it also occurs in the remanie or nodule beds of the Grange Bum 

 and Beaumaris, whose material was probably derived from an 

 underlying Janjukian stratum. This same species, u. retro- 

 flexa, occurs in the Oamaru Stone of the S. Island of N. Zea- 

 land, and described under the name of Oxyrhina vonhaasti by 



1 This species w.is iiconied also troni ("oiio I'.;iy Im error for Batesford (Prod. Pal. Vict., 

 dec. vii., 1882, p. IG). The specimen has tlie test badly crushed, but .shows some 

 characters intermediate between L. [lifjan and L. inoorahoolensis, I'ritch. 



2 Sep Hutton, Trans, and Proc. N.Z. Institute, vol. xxxvii., 1905, p. 481. 



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