1919.] NATURAL SCIENCES OF PHILADELPHIA. 191 



femora black except the broad apices. All pile black except on 

 second and third abdominal segments. Length, 6-7 mm. 



9 . Similar but the yellow on segments 3, 4, 5, with sublateral, 

 rectangular prolongations basally and the medial wedge attains 

 base of fifth; sixth segment yellow with two black apical converging 

 stripes. Femora yellow except fore one above; and hind one with 

 subapical black ring. All pile black. 



Type.— d"; Colorado [A. N. S. P. No. 6211]. Paratijpe.—l 9 , 

 Mokelumne Hill, Calaveras Co., California, August, (F. E. Blais- 

 dell), [Cal. Acad. Sci.]. 



ORTALID^. 

 Rivellia cognata new species. 



Same as flavimana Lw. but the legs are entirely yellow excepting 

 that the hind tibiae and apices of tarsi are brownish, but never black. 

 The wing markings are similar. 



Type. — d^ ; Swarthmore, Pennsylvania, June 11, 1905, (E. T. 

 Cresson, Jr.), [A. N. S. P. No. 6212]. Paratypes.—2d^, 1 9 ; topo- 

 typical. 



A series of seventeen specimens from the following localities: 

 Pennsylvania: Manayunk, Philadelphia, Swarthmore. New York: 

 Ithaca. New Jersey: Medford. Georgia. Florida: St. Petersburg. 

 Wisconsin: Beaver Dam. It seems to be more common than flavi- 

 mana in collections. There is much to suggest Herina metaUica v. d. 

 Wulp, but I cannot find any reference in the description of or in 

 the figure of that species that the costal cell is entirely infus- 

 cated. The figure shows the infuscation only at the extreme base, 

 while vnih the present form this color extends to the first band as 

 it does in flavimana. There should not be any confusion between 

 the present form and qiiadrifasciata. In that species the first basal 

 cell is entirely infuscated and the abdomen often rufous, and on the 

 whole is a much more robust species. 



SEIOPTERA Kirby and Spence. 



1817. Kirby and Spence, Intro. Ent., ii, 305. 

 1830. Myodina Desvoidy, Essai Myod., 727. 

 1867. Seoptera Loew, Bed. Ent. Zeit., xi, 29.5. 



This genus was proposed in a very meagre way, but as a species 

 is included in the original citation, the name is valid. It is based 

 on Musca vihrans Linn. (1761). The limit of the genus has been 

 very much restricted as only one or two species are known to belong 

 to it. 



