154 JOUKNAL OF SCIENCE. 



It seems that during the Secondary period there were four more 

 or less continuous lands; three archi-continents formed, an arctic, 

 an antarctic and a tropic atlantic. The first is identical with Heil- 

 prin's holarctic region. The connexion between Europe and North 

 A merica must haye been more extended, whilst there was, up to the 

 tertiary period, no land communication Vith South America, or at 

 least only formed by a number of islands. 



The connexion between South America and Africa seems to be 

 confirmed also by the as yet but little studied Najadce. The African 

 Iridina and Spaflia have their nearest allies in Mycctojms and Anodonta 

 of South America. Iridina, or similar forms, are also found in the 

 eocene fresh-water deposits of Brazil, which very likely are erroneously 

 considered by White as cretaceous. Even in Australia and Asia we 

 find a Mycctyms or allied genus. Those fragile, elongated, iriclina-like 

 forms are therefore those which appear next to Unio. Their scanty 

 distribution in Australia and absence from New Zealand and Chile 

 show that the land-bridge which once existed between Australia and 

 the Indo-Malayan territory disappeared during, or shortly after, the 

 cretaceous epoch, at which time the immigration of Mycetojms had 

 taken place. H ad it been longer in existence, Australia would also 

 have received a stock of placental mammals ! The tertiary genera of 

 the Najadcu and the Amyullari<i> could therefore not reach Australia 

 nor New Zealand. 



Many observations on the structure of the umbo seem to prove a 

 near connexion between the African and South American Unio, but 

 only the examination of the animals can solve the question. 



Additional to the archiboreal and archiatlantic continents there 

 would be the archiaustral continent, reaching from Chile over New 

 Zealand to Australia. 



The study of ihe fresh-water fauna will help us principally or 

 perhaps exclusively to gain a proper knowledge of the geographical 

 distribution of the organisms during the Secondary epoch as well as 

 for the distribution of land and water during that period. 



ON THE GREAT OAR-FISH.* 



BY H. O. FORBES. 



On the morning of the 28th of May I received a note from Mr. 

 Warnes, the fishmonger, requesting me to inspect a curious fish 

 caught in Okain's Bay, Banks Peninsula, on the 26th, and which he 

 was bringing up to town that day. On its arrival in Christchurch in 

 the afternoon I found the fish to be a species of Eegcdecus, or oar-fish 

 of unusually large proportions. 



Regahciis is a genus of fishes belonging to the family Trachyp- 

 teridcv, or ribbon-fishes. According to Dr. Giinther, of the British 



* A paper communicated to the Philosophical Institute of Canterbury. 



