328 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



of sheath 1.9 to 4.9 (sheath measured in flattened condition, only ex- 

 posed dorsal portion measured); apical portion of ovipositor (oviposi- 

 tor proper) translucent reddish yellow, dorsoventrally flattened, 

 lanceolate, with variable tip either arrowheadlike, somewhat de- 

 limited, with minute dorsal hook at apex, or simple. 



In the present paper, as in former publications, the writer has sought 

 new and better taxonomic methods and, considering the species as 

 natural units, has attained satisfactory results. The more extensive 

 application of morphological and biometric methods undoubtedly 

 would be advantageous for the development of entomological tax- 

 onomy. 



The genus Tomoplagia represents a phylogenetically homogeneous 

 group which it would be unnatural to divide into further genera. In 

 this genus there are many species with very similar wing pattern, as 

 in other genera of the family Tephritidae (e. g., in Xanthaciura, Para- 

 stenopa, Rhagoleiis, etc.) and some species with distinctly different 

 pattern. It is very interesting to find four species in this genus, 

 each of which, with regard to a conspicuous character, has a counter- 

 part or "twin" species; these are penicillata-pseudopenicillata (special 

 armature of the mid tibiae), atimeta-kelloggi, discolor-pura, incompleia- 

 argentiniensis (each pair with a special wing pattern). 



The most highly developed and at the same time most crowded 

 groups of Tomoplagia are apparently the obliqua-monostigma-minuta 

 (excluding kelloggi and incompleta) and the pleuralis-reimoseri groups. 



There are, however, many highly specialized species which cannot 

 be placed in groups, such as propleuralis, atimeta, kelloggi, carrerai, 

 qtuidriseriata, quadrivittata, Jiebrigi and unifascia. 



In this genus the following principal tendencies of evolution can be 

 noted: Toward the reduction of the anterior ori, posterior ors, poste- 

 rior npl, inferior mpl, apical sc bristles; toward the reduction of the 

 black ground color of the thorax and abdomen; advance of the dc 

 and prsc {=acr) bristles toward the anterior region of the thorax; 

 and toward the reduction of the posterior pair of gonapophyses in the 

 male postabdomen. 



The modern form of the epandrium and the dense dusting of the 

 mesonotum apparently represent progressive characters in Tomo- 

 plagia. 



The following key includes all the known species and is based 

 principally upon the presence of the black spots of the thorax. Since 

 it is not known whether the species pura Curran and tripunctata 

 Hendel have postscutellum black or black-spotted, and since the 

 black spots of the postscutellum in incompleta (Williston) are recently 

 in a state of disappearance, these three species wiU be found in both 

 alternatives of couplet 1. 



