May -24, 1895.] 



SCIENCE. 



587 



graphical Distributiou of tlii' Xaiades,' an 

 abstract of a paper on classification and 

 distribution soon to be published. 



After stating that the classification 

 adopted by most authoi-s, in which the 

 family Unioniihv is founded on forms without 

 siphons, and the Mutelidiv on those in which 

 they are developed, cannot stand, since 

 these characters vary in the same genus or 

 species, the writer showed that von Ihe- 

 ring's new definition of the families, in 

 which the former was based on the embrj'- 

 onie state being a glochkUum and the latter 

 by its larvffi being a lasidium agi'eed with 

 the shells. In the Unionichc these are schizo- 

 dont, in the 3Iutelida' they are irregular!}- 

 taxodont. The new arrangement shows the 

 former family to be world-wide; the latter 

 as belonging essentially to the southern 

 hemisphere. 



The Naiads are distributed in Geograph- 

 ical Provinces whose boundaries may be 

 mountain chains which act as watersheds 

 between river S3'stems, deserts or oceans, 

 but these do not alwaj's divide regions, 

 which sometimes have no tangible barriers. 

 In the Old "World and South America these 

 provinces essentially agree with those es- 

 tablished by Sclater and Wallace ; in North 

 America they do not. 



The Paliearctic Region includes all Asia 

 south to the Thibetan Plateau, and all the 

 western part of the continent, all Europe 

 and northern Afi-ica, and all of North 

 America west of the Great Cordillei-a ; an 

 area of 16,000,000 square miles, with only 

 a few, not over 50, simple forms. The 

 Oriental Region includes all of Asia south 

 of the Himalayas, north to the Amoor, 

 west to the Indus, Japan and the Malay 

 Archipelago to the Salomon Islands. The 

 forms are numerous, often heavy, distorted, 

 elegantly sculptured, and closely related to 

 those of the United States. 



The Australian Region includes Austra- 

 lia, Tasmania and New Zealand, with a 



few simple unios related to those of South 

 America. Africa south of the Desert is an- 

 other great region, the Ethiopian, contain- 

 ing the African Mutelid(r and small unios 

 allied to those of India. South America is 

 all included in another province, the Neo- 

 tropical, the Andes proving a barrier to the 

 passage of all forms except unios, which 

 have crossed to the western slope. All the 

 central United States drainage from West 

 Florida to the Rio Grande, including, for 

 the most part, the Great Lakes and the 

 Mackenzie System, constitutes a wonder- 

 fully rich region of naiad life, having the 

 finest and most varied foi-ms of the globe. 

 The waters of North America draining into 

 the Atlantic are peopled by simple forms, 

 which may have descended from those of 

 the ilississippi A'alley. Mexico and Central 

 America constitute another region of naiad 

 life, having three distinct faunas, an ancient 

 one derived from the United States, a more 

 recent one from that region, and a few im- 

 migrants from South America. 



Mr. Simpson attempts to trace the de- 

 velopment and past historj- of the naiads, 

 and their evidence regarding past changes 

 of land and sea and the Glacial Epoch. 



The paper was illustrated by a sketch- 

 map in colors, showing the difl'erent regions. 



The second paper of the evening, ' The 

 Other Side of the Nomenclature Question,' 

 was by Dr. Erwin F. Smith, who spoke, in 

 reply to a previous paper by Mr. F. X. 

 CovUle, against the unfounded claims put 

 forth in behalf of the Botanical Club Check 

 List. This list has introduced many radical 

 changes into our existing botanical nomen- 

 clature without suflicieut reason. Tlie re- 

 vival of the long disused generic names of 

 Rafinesque et a/., and the retro-active appli- 

 cation of the rule '' Once a synonym always 

 a synonym," whereby many generic names 

 of long standing have been tliscarded, are 

 speciallj^ objectionable, and will not bear 

 the light of criticism. Only a few people 



