1911.] Petrunkevitch, Index Catalogue of American Spiders. 9 



A number of names had to be omitted entirely from both hsts as being 

 invaUd. They are chiefly the names proposed by Marx for new nearetic 

 species which he was never able to describe owing to his untimel}^ death. 

 The specimens in qu^estion have meanwhile been lost, the names are there- 

 fore without any value and may be used eventually for other new species. 

 Simon mentions some new species which he has subsequently neglected 

 to describe owing to some oversight. Since the corresponding specimens 

 probably still exist in the Paris collection, these names will be found in the 

 third part of the catalogue, where will be also found a few names published 

 b}' other authors without any description or figure. A regrettable omission 

 from my catalogue is the majority of the species of Holmberg, described 

 by him in his first paper which I was not able to find in this country. An 

 attempt to procure it from Argentina, where it was published, also failed. 

 These species are also omitted from the lists of the Zoological Record, but 

 are supposed to be largely synonyms of species better described by other 

 authors. A few of them have been redescribed by Keyserling and Simon 

 and will naturally be found in the catalogue. 



The number of species described from the American continent and the 

 adjacent islands is somewhere in the neighborhood of 6000. Some of these 

 will undoubtedly be found to be synonyms, as was the case with so many 

 others. After all we may safely suppose that the actual number of species 

 inhabiting this continent is consideral)ly, perhaps ten times greater. Espe- 

 cially the tropical countries of Central and South America will yield for a 

 long time to come an inexhaustible amount of new forms and will greatly 

 change our conception of the geographical distribution of this interesting 

 group. As it is we still may recognize several regions. Probably the richest 

 region is the equatorial belt merging gradually south into the subtropical 

 and temperate zone of South America and north into the great tropical 

 region comprising ^'enezuela, Colombia and Central America as far as the 

 isthmus of Tehuantepec, the West Indies and extending even into Florida. 

 The forms of the Mexican plateau are found in the southern states. The 

 temperate North American region, comprising about 1200 known species, 

 extends north into Canada and may be split into several smaller regions 

 with the Mexican forms disappearing from it as we proceed northward into 

 Texas and on the coasts into Louisiana and California. The nearetic 

 region comprises few forms, the majority of which are identical or closely 

 allied to the forms found in Iceland and Spitzbergen. Finally comes the 

 Patagonian region with its interesting primitive forms not encountered 

 anywhere else on this continent. A few spiders, like the poisonous Latro- 

 dectus viadans, are found all the way from New Hampshire to the Terra 

 del Fuego. Some European species are as common in the United States 



