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PART I. 



EXTENT AND CHARACTER OF THE COLLECTION. 



About six hundred and fifty Arachnids were collected by this 

 expedition, making the collection by far the largest ever brought 

 from the Galapagos Islands. The specimens belong to forty- 

 eight species which fall in the three great groups of Arachnida 

 as follows : Araneida, thirty-nine species ; Arthrogastra, six 

 species ; Acarina, three species. 



The thirty-nine spiders represent fifteen families, of which 

 the EpeiridcE have nine species, the Attidee five, fhe Theridiidae 

 four, the Sparassidae and Lycosidee three each, while the other 

 families are represented by but one or two species each. 



Twenty-five species are considered new, and are here first 

 described ; two are classified only generically ; twenty-one are 

 known species, of which four are peculiar to these islands. The 

 collection contains, with two exceptions, specimens of all species 

 ever taken on these islands. The exceptions are Segestria 

 ceqtiatoria of Marx's manuscript, and his young Agalena. 



The first spider known from these islands — Gasteracantha 

 insulana — was described by Thorell in 1859. ^^ ^'^'^^ been taken 

 by all subsequent collectors. In 1877 Butler published in the 

 Proceedings of the Zoological Society of London a list of the 

 species collected by the Petrel expedition. In 1889 Dr. Marx pub- 

 lished a list (without descriptions) in the Proceedings of the U. S. 

 National Museum of the species collected by the Albatross expe- 

 dition. These lists together include not more than thirteen spe- 

 cies, though appearing under sixteen names. They are as follows : 



Recorded by Butler. Recorded by Marx. 



Androctonus americus Linn. Segestria ceqtiatoria sp. nov. 



Lycosa indomita Nicolet. Agalena (immature). 



Theridiuin caroli7iu?n sp. nov. Loxosceles galapagoensis sp. nov. 

 Lathrodectes apicalis sp. nov. Filistata oceanea sp. nov. 

 Gasteraca7itha insulana Thorell. Lathrodectes apicalis Butler. 

 Epeira cooksonii sp. nov. Lathrodectes scelio Thorell. 



Thomisoides uUrifor7nis sp. nov. Gasteracantha insulaiia Thorell. 



Epeira cooksonii Butler. 



Heteropoda venatoria Linn. 



Alenemertts galapagoc7zsis sp. nov. 



Ce77truroides luctifer sp. nov. 



Vejovis galapagoe7isis sp. nov. 



