SOME ARACHNIDA FROM CALIFORNIA. BY NATHAN BANKS. Plates XXXVIII-XLI. The following pages include a list of spiders and other Arachnida sent me for determination by the California Academy of Sciences, together with other Californian material received from several collectors. The arachnid fauna of California is undoubtedly very large, so that this list is far from complete; yet it is full enough to show some of the more striking peculiarities of the fauna._ The abundance of Pseudoscorpions and Phalangid£e is not equaled elsewhere in the country. There is a larger proportion of Thomisidas and Drassidas than is found in the eastern parts of the country. In Southern California there are a few species of a tropical aspect. In the northern parts, particularly from Mount Shasta, there are various spiders common to the northern parts of this country and of Europe. It is a notable fact that these northern spiders extend farther southward in California than they do in the Eastern States. Since Atlantic latitudes are colder than Pacific ones, it follows that these spiders flourish in California in a much warmer average temperature than they are accus-tomed to in the East. Altogether there are two hundred and six Arachnida re-corded in this list; one hundred and fifty-three spiders, and fifty-three of the other groups. The spiders belong to twenty-one families, eight of which are represented by but one species each. The largest family is the Attidas with twenty-four species; then follows the Theridiid^ with twenty; the Epeiridse and Thomisidse each have eighteen. Of the other groups the Acarina and Phalangida have each nineteen species. (i) [ 331 ] November 29, 1904.