E. T. CRESSON, JR. 27 



A REVISION OF THE NEARCTIC SCIOMYZIDAE 

 (DIPTERA, ACALYPTRATAE) 



BY E. T. CRESSON, JR. 



In working over a collection of acalyptrate Diptera from Cor- 

 nell University, Ithaca, New York, the material representing 

 this family was found to be quite extensive and possessed a number 

 of new" or little known species, so that a rather serious study of 

 the family was undertaken. Through the kindness of Mr. Charles 

 W. Johnson, I was able to examine many European species, 

 including the genotypes of most of the known genera. He also 

 furnished much interesting material from his collection, and, 

 through him, from the collection of the Boston Society of Natm-al 

 History. With the above mentioned material, and some from 

 various other sources at hand, I felt a revision of the North 

 American species, especially of the eastern United States, would 

 make an acceptable contribution towards the knowledge of this 

 family. Therefore from rough notes and descriptions of new 

 forms made several years ago, originally intended for casual 

 publication, augmented by re-descriptions of most of the known 

 species, the construction of the present paper was attempted. 

 After many interruptions in such preparation, it is offered, with 

 full knowledge of its many gaps in composition and completeness. 



The first collective work on our species is that by Loew in the 

 first volume of his monographs. Since then there have been 

 quite a number of isolated descriptions l)y Loew, Coquillett and 

 Day. In 1900' and 1902^ Hendel published revisions of the 

 European species, erected some new genera, and adopted some 

 of the little understood genera of Desvoidy and others. With 

 the aid of these works, we are able to study our species more 

 satisfactorily, and they have, of course, made this paper of mine 

 a possibility. In several cases I have had to make an extensive 

 study of the literature, which resulted in some important and 

 not agreeable changes in the nomenclature of some of the genera. 



'Verh. Zool.-Botan. GeselL, Wien, I, 319, 1900. 

 2Abh. Zool.-Botan. Gesell., Wien, ii, heft 1, 1902. 



TRANS. AM. T.NT. SOC, XLVI. 



