NOTES ON GEOGRAPHICAL DISTRIBUTION. 25 1 



fishes for further development, and fresh-waters containing no fish are 

 also devoid of Najadce. Dr. von Jhering never found embryos of 

 Najadce on the skin of South American fishes, and it will be the same 

 with those of New Zealand. The embryos of the South American and 

 New Zealand Najadce possess neither the sharp and angulated rudi- 

 mentary shell, nor a byssus to fix themselves on the skin of fishes, and 

 very probably begin their existence in the sand or mud of the water, 

 after having been expelled from the mother mussel. 



Now this is evidently conclusive proof of a former land communi- 

 cation between New Zealand and South America, as the Najadai 

 cannot live in brackish or salt water, and I think it very likely that 

 the Najadce of Australia and Tasmania will show no difference in the 

 mode of hatching the embryos and the structure of the latter. 



Besides the Unio we have some more mollnsca very nearly allied 

 to those of South America, especially of Chile. Carthcea Kiwi, Gray, 

 belongs to the family of the Orthalicidse, found in South America, 

 which are mostly living on trees. Our shell has retained this mode of 

 living, as the leaf-sheaths of the Nikau palm are a favourite hiding- 

 place for it. Amphidoxa, of which 10 species are known in our colony, 

 and of the Patulidaj the group Stephanoda may be common to Chile 

 and New Zealand, though the dentition of the American species is not 

 known. Tomatellina and Recdia also are found in both countries. 

 There is another of our land shells which will perhaps prove to be 

 closely allied to South American forms, namely, our Dandebardia 

 neozelanica, Pf., of the Waikato district. 1 think Pfeiffer was quite 

 wrong in jilacing this mollusc in the genus Dandebardia, which is 

 known only from some parts of Europe, Western Asia, and Algeria. I 

 have but litle doubt of its belonging to a South American genus, but 

 the question can only be decided on examining the animal. I have not 

 been able to obtain it either alive or preserved in spirits, but should be 

 greatly obliged to anybody who could procure it for me. 



Very little is yet known of the anatomy of the land and fresh- 

 water shells of most parts of the Southern Hemisphere, though New 

 Zealand in this regard no doubt takes first rank. But of the land and 

 and fresh-water mollusca of Tasmania, of a great part of Australia, 

 Polynesia, and western South America, we know very little beyond the 

 descriptions of the shells. Judging from the form of the shells only it 

 is very hazardous to say which forms are nearly allied, and one might 

 very often be mistaken. I will only mention here that Mr. Ch. Hedley 

 of Sydney, on examining the animals of shells from Lord Howe Island, 

 which he and Mr. Brazier considered to belong to the genus Rhytida, 

 found them to be Patula. I have had similar experiences here in New 

 Zealand. Hyalina corneo-fulva, Pf, I found to belong to the genus 

 Amphidoxa, and what I considered to be a Diplomphahis has proved to 

 form a peculiar group of Patula. 



I have satisfied myself that the land and fresh-water fauna of the 

 Southern Hemisphere, with the exception of a few cosmopolitan genera, 

 is entirely different from that of the Northern Hemisphere, much more 

 so than the concholojrists of the latter admit. 



