590 Dl{. A. HORLET DAVTES OX THE FAUNAS [vol. lxxix, 



where. That the Orbiculina Limestones are later than the O.- 

 virleti Beds was inferred by Mr. Wayland from the stratigraphical 

 evidence (p. 582), and is independently suggested by the re- 

 stricted geographical distribution of that very striking foraminifer. 

 It is true that, from Kebang Sokkoh, in Java, Martin has 

 described an Orbiculina associated with other foraminifera, such 

 as occur with O- malabarica in Ceylon (Jflosculinella, Sorites, 

 abundant Miliolidse) ; but the Java species exhibits characters 

 suggestive of an ancestor of O. malabarica (longer persistence 

 of the spiral stage), and it is associated with Miogypsina in 

 abundance, whereas no trace of that genus has yet been found 

 in Ceylon. 1 The only certain occurrence of O. malabarica outside 

 Ceylon is near Quilon in Travancore (Carter, 1857), about 200 

 miles west of its Ceylon occurrences. It seems certainly absent 

 from Kach, and in Egypt the first invasion of the Indian Ocean 

 is marked by the Pecten-vasseli fauna, which (as no trace of it 

 has been found in Ceylon) probably belongs to a later date than 

 O. malabarica. 



The identity of the Quilon beds with those of Northern Ceylon 

 can hardly be doubted. In addition to O. malabarica, Carter 

 recorded a few gastropods, all identified with species from Kach or 

 Sind. Only one of these, Cerithinm rude, appears also on our 

 list ; another is given by Fedden as a pre-Oaj form, and the 

 remainder are not dated by him at all. Though the gastropods do 

 not go far, therefore, to support the evidence of the foraminifer, 

 they do not traverse it; and large foraminifera are generally 

 more restricted in range, and therefore more useful for dating, 

 than gastropods. 



The other marine Neogene fauna to which we naturally look for 

 comparison is that of Karikal, on the Coromandel coast, about 

 SO miles almost due north of Kirimalai. The gastropods of this 

 fauna, which are beautifully preserved, have been described by 

 Dr. Cossmann (1900-03-10). It is rather surprising that, in 

 only very few cases, can any of the Karikal species be even 

 a pproximately identified in Ceylon, and on the other hand that 

 such striking forms as the large Conns brevis should apparently 

 be wanting at Karikal. The Karikal fauna is regarded by Dr. 

 Cossmann as Pliocene ; but Vredenburg, in his diagram of the evolu- 

 tion of the Indian Ocean fauna (1912) placed it on the level of the 

 Upper Hinglaj (Vindobonian). To us it appears to be probably 

 separated from the Orbicvlina-malabarica Beds by a gap wider 

 than that between the latter and the Ostrea-virleti Beds of 

 Southern Ceylon. If these last be Vindobonian and probably 

 Upper Vindobonian (Tortonian), the O. -malabarica Beds must be, 



1 The limestone of Minihagalkanda contains foraminifera which, when 

 more fully studied, may help in the more exact determination of its age. 

 Owing to the compact nature of the rock, only chance sections can be studied ; 

 and, in view of the already long delay in the completion of this paper, it did 

 not seem wise to wait for a complete series of sections of the available 

 material. 



