2 20 NILS HJ. ODHNER 



Otherwise not in the Peruvian Province); to the northern, for instance, Lima 

 angulata (Gulf of Panama to J. Fernandez). 



Except for the species of Eiiplocamus and Ervilia which genera are not 

 represented on the shores of S. America, ail endemic forms show relations to 

 the American fauna, above all to that of the Peruvian Province; only a few 

 have their nearest allies in the Magellanic Province (such as Avicula aequivalvis) 

 or in the southernmost part of the Peruvian Province (Onchidium juanfernan- 

 dezianum). A northern origin is likely as regards Venerupis fernandeziana,i\ie 

 genus being represented by a second species occurring from Panama to N. Peru. 

 The one of the endemic genera, Jiianella, speaks in favour of an origin 

 from the southern part of the S. American coast (the closely allied Tyrinna is 

 established on a species from Calbuco), whereas the second genus, Aplysiopsis, 

 lacks allies within the same districts, the genus Aplysia (= Tethys) occurring 

 i. a. within the Peruvian Province and in the Pacific. 



The summary is, that the marine mollusc fauna of Juan Fernandez shows 

 a closer relation to the American than to the Indo-Pacific one, and that the 

 great quantity (50%) of endemic species indicates a long isolation. 



About the terrestrial moUusca of Juan Fernandez, which are by far more 

 abundantly collected by the Swedish expedition than the marine ones, no 

 comprehensive report has been issued hitherto. There are only scattered de- 

 scriptions and notes published on them. None has been made subject to a 

 detailed anatomical investigation; our knowledge has been merely superficial, 

 and their relation has been settled in a few cases only, above all by the works 

 of PiLSBRY (Man. of Conchology, ser. 2, vol. 9, 1894 — 95, and 21, 1910— 11), 

 who also quotes the few authors having written on this subject. 



But for a few sp&cies, (Agriolimax agrestis, Limax arborum, Milax gagates, 

 Helix aspersa, Hyalinia cellaria and alliaria), which have been introduced in 

 recent times, the terrestrial mollusca of Juan Fernandez are all endemic species. 

 The islands have no species in common with other districts. There are indi- 

 genous representatives of three families only, Endodontidae, Tornatellinidae, 

 and Succineidae, all of great age comparatively; more recent and highly dif- 

 ferentiated families, such as Helicidae, are entirely wanting in the original fauna. 

 Of Endodontidae there is one endemic genus, Amphidoxa, closely -related to 

 Stephanoda, which is exclusively S. American (mostly in the south-western 

 shore-parts of the Continent). The remaining genera, Ptmctum and Endodonta, 

 are not at all represented in the Neotropical Region, the former being hmited 

 to the Northern Hemisphere, and the second to Australasia and Polynesia. The 

 fam. Tornatellinidae comprises two genera endemic in Juan Fernandez, Torna- 

 tellina and Fernandezia; both show a remarkable relation to Pacific groups 

 (the new genus Pacificella from Easter Island), and are also allied to the Hawaiian 

 fam. Achatinellidae. Succinea is a genus of world-wide distribution; the Juan 

 Fernandez species seem to be allied partly to Pacific and partly to S. American 

 forms, and Otnalonyx, which seems closely related to certain Juan Fernandez 

 species of Succinea, has one of its representatives in these islands, the other 

 one on the S. American Continent. 



By the Swedish expedition the following marine mollusca were collected 

 (an asterisk signifies that they are previously recorded; cf. Dall): 



