part 4] OF THE MIOCENE OF CEYLON. 591 



at the earliest, very late Vindobonian, and may be as late as 

 Pontian (or rather Sahelian, as they are marine), while the Karikal 

 beds could not be earlier than Pliocene. 



[Postscript. I am indebted to Dr. H. Sadelc for information 

 concerning the Miocene of Egypt, which suggests slight modifica- 

 tions in the foregoing conclusions. He has found evidence of 

 temporary communication between the Mediterranean and Indian 

 Oceans at two distinct dates in the Vindobonian epoch — one at its 

 very commencement, the other much later. Oysters of the O.- 

 virleti type were already established in Egypt before the earlier 

 of these connexions, in late Burdigalian times, and they range to 

 the local summit of the Vindobonian. It would, therefore, seem 

 more probable that O. virleti migrated from Mediterranean to 

 Indo-Pacific areas than vice verm. At the same time, the date of 

 the Minihagalkanda beds becomes a little less certain. While the 

 negative evidence of the foraminifera would seem to exclude any 

 probability of a Burdigalian date, thej" may belong to the 

 opening of the Vindobonian epoch, instead of to the later date 

 within it suggested above. — A. M. D., October 25th, 1923.^ 



Palseontological Details. 



Orbiculina malabarica (H. J. Carter). (PI. XXVIII, figs. 1-4.) 



1853. Orbitolites malabarica H. J. Carter, Ann. Mag - . Nat. Hist. ser. 2, 



vol. xi, p. 425 & pi. xvi B, figs. 1-4. 

 1856. A fossil Orbiculina W. B. Carpenter, Phil. Trans. Royal Soc. 



vol. cxlvi, p. 549 & pi. xxviii, figs. 17-19. 

 1902. Orbiculina malabarica H. Douville, Bull. Soc. Geol. France, ser. 4, 



vol. ii, pp. 300-301. 



Compare also : — 



1917. Orbiculina. cf. adunca Ficlitel & Moll, Martin, Samml. Geol. Reichs- 

 Mus. Leiden, n. s. vol. ii, pt. 7, p. 277 & pi. v, fig. 142 (Miocene of 

 Java). 



Test (plasmostracum) discoidal, thin ; maximum diameter 

 observed=21 mm. ; thickness=0*75 mm. Cyclical growth not 

 fully attained until a diameter of 3 to 5 mm. is reached. Large 

 forms probably all microspheric ; largest observed diameter of 

 megalospheric form = 5 - o mm. Diameter of megalosphere=0 - 33 

 mm.; diameter of spiral passage around megalosphere=O06mm, 

 Microsphere not certainly seen. 



The mode of shell-growth is that typical of the genus, and has 

 been fully described by Carpenter. Prom the recent type-species 

 O. adunca Fichtel & Moll, it is readily distinguished by its large 

 size, and the perfect cyclical growth of the greater part of the 

 disc, despite the more prolonged period of spiral growth. From 

 the Miocene form described by Martin from Java it differs in 

 exactly the opposite way, in having spiral growth restricted to 

 early life instead of continuing throughout life (or at least up 



