LIST OF ILLUSTRATIONS XI 



TEXT FIGURES 



New dipteba or two-winged flies from South America 



By J. M. Aldrich 



Facing page 



1. Daetaleus purpureus. Genital segments and genitalia of male from 



left side: 1, 2, genital segments; if, inner forceps; of, outer forceps; 



cl, clasper; p, penis 14 



2. Piriona fasciculata, new species. Hind leg of male 25 



Fossil footprints from the Fort Union (Paleocene) of 



Montana 



By Charles W. Gilmore 

 1. Ammobatrachus montanensis. Diagram of trackway 2 



A revision of the wood-warbler genus Basileuterus and 



its allies 



By W. E. Clyde Todd 

 1. Diagram of the phylogeny of Basileuterus and allied genera 



A NEW polychaetous annelid of the genus Phyllodoce 



FROM the west COAST OF CoSTA RiCA 



By Aaron L. Treadwell 



1-3. Phyllodoce nicoyensts, new species: 1, prostomium and proboscis; 

 2, parapodivim ; 3, seta 



Tschermigite, ammoniojarosite, epsomite, celestite, and 



PALIGORSKITE FROM SOUTHERN UtAH 



By Earl V. Shannon 

 1. Celestite crystal. Panguitch. Utah 



A REVISION OF THE NoRTH AMERICAN ICHNEUMON-FLIES OF THE 

 GENUS MeSOSTENUS AND RELATED GENERA 



By R. A. Cushman 



Head of: a, Listrognathus albomaculatus (Cresson), dorsal view; b, same, 

 lateral view of lower part to show occipital carina (oc) and hyposto- 

 mal carina (he); c, Listrognathus agnatus Cushman, lateral view of 

 lower part; d, Polyaemis spinarius (Brulle), dorsal view; e, Mesos- 

 tenus leucopus Ashmead, dorsal view; /, Polycyrtus neglectus Cush- 

 man, dorsal view; g, Polycyrtidea limitis Cushman, dorsal view 



First abdominal segment of female: a, Agonocryptus discoidaloides 

 (Viereck), lateral view; b, Messatoporus discoidalis (Cresson), lateral 

 view; c, Mallochia agenioides Viei'eck, dorsal view; d, same, lateral 

 view; e, Listrognathus albomaculatus, lateral view; /, Crypturopsis 

 audaz (Cresson), dorsal view; g, Mesostenus leucopus Ashmead, 

 dorsal view; h, same, lateral view 



Propodeum of female: a, Crypturopsis abdominalis Cushman; b, Agono- 

 cryptus discoidaloides (Viereck) ; c, Messatoporus discoidalis (Cres- 

 son); d, Listrognathus albomaculatus (Cresson); e, Listrognathus agna- 

 .tus Cushman; /, Diapetimorpha introita (Cresson); g, Derocentrus 



