_Andrena peratra_ sp. n. Prov. Det. Ckll. Claremont, Cal., Baker. _Andrena auricoma._ Sm. Det. Ckll. Claremont, Cal., Baker. _Andrena plana._ Vier. Det. Ckll. Claremont, Cal., Baker. _Andrena opaciventris_ sp. n. Ckll. Det. Ckll. Claremont, Cal., Baker. _Andrena chlorura_ sp. n. Ckll. Det. Ckll. Claremont, Cal., Baker. _Agapostemon splendens._ Friese Des. Lange. Los Angeles, Cal. _Agapostemon californicus._ Crawford. Claremont, Cal., Baker. May, Poppy. _Agapostemon radiatus._ Say. Det. Br. from Coll. Claremont, Cal., Bray. April, Fl., Daisy. _Diandrena beatula_ sp. n. Ckll. Det. Ckll. Claremont, Cal., Baker. _Diandrena chalybæa._ Cr. Det. Ckll. Claremont, Cal., Baker. _Diandrena cyanosoma_ sp. n. Ckll. Det. Ckll. Claremont, Cal., Baker. _Diandrena clarventris_ sp. n. Ckll. Claremont, Cal., Baker. _Diandrena scintilla_ sp. n. Ckll. Det. Ckll. Claremont, Cal., Baker. _Conanthalictus bakeri._ Crawford Det. Ckll. Claremont, Cal., Baker. _Conanthalictus macrops_ sp. n. Ckll. Det. Ckll. Claremont, Cal. Baker. _Augochlora pomoniella._ Ckll. Det. Ckll. Claremont, Cal., Baker. _Andrena candida._ Sm. Det. Ckll. Claremont, Cal., Baker. _Andrena angustitarsata._ Vier. Det. Vier. Claremont, Cal., Baker. _Andrena huardi._ Vier. Det. Vier. Claremont, Cal., Baker. _Andrena pallidifæva._ Vier. Det. Vier. Claremont, Cal., Baker. _Andrena cyanosoma._ Ckll. Det. Vier. Claremont, Cal., Baker. _Andrena nigripes._ Prov. Det. Vier. Claremont, Cal., Baker. _Andrena scripta._ Vier. Det Vier. Claremont, Cal., Baker. _Andrena subtristis._ Ckll. Det. Vier. Claremont, Cal., Baker. CERITINIDÆ _Ceratina neomexicana punctigena_ sub. sp. n. Ckll. Det. Ckll. Claremont, Cal., Baker. HALICTIDÆ _Halictus incompletus._ Craw. Det. Mountains near Claremont, Cal., Baker. _Halictus punctatoventris._ Craw. Claremont, Cal., Baker. _Halictus nigrescens._ Craw. Claremont, Cal., Baker. _Halictus catalinensis._ Craw. Det. Ckll. Claremont, Cal., Baker. _Halictus ligatus._ Say. Det. Craw. Claremont, Cal., Baker. _Halictus robustus._ Craw. Det. Claremont, Cal., Baker. _Halictus mellipes._ Craw. Det. Claremont, Cal., Baker. _Halictus farinosus._ Sm. Det. Craw. Claremont, Cal., Baker. _Halictus rhoptoides._ Craw. Det. Br. from Coll. Claremont, Cal., Bray. April, Daisy. COLLETIDÆ _Colletes californicus._ Prov. Claremont, Cal., Baker. _Colletes guadialis._ Sm. Det. Ckll. Claremont, Cal., Baker. PROSOPIDÆ _Prosopis episcopalis_, female. Ckll. Det. Metz. Claremont, Cal., Baker (Rhus laurina). _Prosopis coloradensis._ Ckll. Det. Metz. Mountains near Claremont, Cal., Baker. _Prosopis polifolii_, female. Ckll. Det. Metz. Mountains near Claremont, Cal., Baker. PANURGIDÆ _Panurginus atriceps._ Ckll. Det. Cr. Claremont, Cal., Baker. (_Contribution from the Zoological Laboratory of Pomona College_) A Partial List of the Mammals of the Claremont Region LEON L. GARDNER