SEPTEMBEE23, 1898.] 



SCIENCE. 



395 



reaching that its history, however complete 

 and exhaustive, a year later requires to be 

 re-written ; and there is no reason for sup- 

 posing that the end, or even the beginning 

 of the end, has been reached. With new 

 materials and new methods, and new 

 workers who will profit by the experience 

 and results gained by those who have in 

 our time accomplished so much, we may 

 expect for the new century far greater re- 

 sults than those briefly recorded here. 



It would be difficult just here to pi-edict 

 the future of astronomical photography, 

 though one can foresee something of the 

 great results it must accomplish. It will 

 displace some of the visual work, but it is 

 more likely to move along new lines, open- 

 ing up new fields of research. The older 

 astronomy, so nobly represented by Simon 

 Newcomb and a few others, will be 

 strengthened at every point, and will stand 

 all the more sublime for the help it shall 

 receive from photography. 



E. E. Barnard. 



Ykekes Obseevatoey. 



THE ZOOLOGICAL SECTION {F) OF THE 



AMERICAN ASSOCIATION FOR THE 



ADVANCEilENT OF SCIENCE. 



This section had a successful meeting. 

 Papers of both a general and special na- 

 ture were presented. The address of Vice- 

 President Alpheus S. Packard, entitled 'A 

 Half-Century of Evolution, with Special 

 Reference to the Effects of Geological 

 Changes on Animal Life,' has appeared 

 in this Journal. A brief outline of the 

 papers read is presented in the follow- 

 ing: 



Evolution and Migration of Saivaiian Land 

 Shells. By Professor Alpheus Hyatt. 

 The author studied about 22,000 shells, 



of which 18,000 at least were from Oahu. 



In that island there are about 280 species, 



as compared with about 140 in all the other 



islands of the group. There are three leading 

 genera, Balimella, Achatinella and Apex. 

 The distribution of the species of these gen- 

 era was represented on a large relief map 

 of Oahu, by means of colored pins, con- 

 nected by similarly colored threads. Each 

 pin or series of pins represented a species, 

 as indicated by attached labels. 



All the shells probably sprang from a 

 common ancestor, Achatinella phceozona G., 

 which has become extinct in late years. 

 Starting in the valley Kiliouou, as the shells 

 migrated northward, there was an evolu- 

 tion of species and genera as plotted on the 

 map. The principal occurrence of these 

 mollusks is on the western flanks of the 

 eastern range. The BulimelliB inhabit the 

 highest sides of the mountains, crossing to 

 the eastern side, and there evolving a con- 

 siderable number of species. This genus 

 does not succeed in forming colonies in the 

 range on the western crest of the island. 

 The Achatinellse occupy a lower zone below 

 both the Bulimellse and Apex. They cross 

 to the eastern side of the mountains in sev- 

 eral places ; but are unable to contend suc- 

 cessfully with the climate on that side. 

 They were also unable to cross the valley 

 lowlands in the center of the island, except 

 in sporadic cases. The species of Apex 

 occupy a middle zone, between the Bulimel- 

 lse and Achatinellse, on the western flanks 

 of the eastern range. They seem more 

 delicate, and less able to contend with the 

 surroundings on the ocean side of the hills. 

 Not a species has been recorded from that 

 side ; but, on the other hand, it crossed the 

 broad plain of the interior, and was suc- 

 cessful on the short western range, where 

 only a few sporadic species of the Achati- 

 nellse are found. The evidence is that 

 the species are distributed over the island 

 in definite lines, which correspond to defi- 

 nite geographical areas. In the oldest part 

 of the island are the oldest forms as evi- 

 denced by development. 



