_Types_: Catalogue No. 20357, U. S. National Museum, the female on a tag, a fore wing antenna and hind leg on a slide. In the U. S. National Museum a female from the Santa Cruz Mountains, California, part of the type of _coquillettii_ (now a single female from Los Angeles). _Eusandalum obscurum_ n. sp. The type is one female from Easton, Washington (Kincaid). Catalogue No. 20358, U. S. National Museum, the female on a tag. See table. _Eusandalum alpinum_ n. sp. The type is a part of the type of _coquillettii_ from the Santa Cruz Mountains, California; Catalogue No. 20359, U. S. National Museum, the specimen on a tag. See table. _Eusandalum georgia_ n. sp. One female, pinned, Georgia, Catalogue No. 20369, U. S. National Museum. A second female from Washington, D. C. See table. _Eusandalum arizona_ n. sp. A female, Santa Rita Mountains, Arizona (Schwarz), May 27. Catalogue No. 20361, U. S. National Museum, tag. See table. Synopsis of the North American Species of _Eusandalum_. Females. (From the types.) 1. Wings bifasciate, the distal fuscous band at apex. Legs red except the coxae, the antennae wholly concolorous. Ovipositor extruded for over half the length of the abdomen. Scutellum longitudinally lined. Hyaline band of fore wing distinctly narrower than either fuscous band (one on each side of it); stylus a little shorter than the ovipositor. _californicum_ Girault Hyaline band of fore wing somewhat broader than either fuscous stripe; stylus and ovipositor equal. _coquillettii_ Ashmead 2. Wings unifasciate or wholly embrowned or with a large unbroken, fuscous area. Wings wholly infuscated. Scutellum densely punctate like the scutum (in the first species). Propodeum with a lateral sulcus. Ovipositor much extruded. Legs reddish except the coxae and the first and third femora _ventrad_; more slender than usual, the ovipositor about as in _californicum_ but the abdomen is longer, hence the ovipositor is so. Fore wing with a longitudinal white streak caudad of middle. _acmaeoderae_ Rohwer Ovipositor extruded for less than a fourth the length of the abdomen, the stylus subobsolete. Fore wings indefinitely slightly stained; legs reddish except the coxae; scutellum long-lineolated. _obscurum_ Girault Wings infuscated from the bend of the submarginal vein to apex or nearly. Antennæ concolorous (compare _obscurum_).