E. T. CRESSON, JR. 
329 
(lemandata and M. frit P'abricius) and a note' niad(' r('f('rrin<>- 
the genus, as he considered it, to his group “Soinl)res on nietal- 
liques division des M. vibrantes.” In referring to Latreille’s 
earlier work-*, under the division mentioned we find thre(' specie's 
cited; Musca vibrdus, frit?, and subsidtanH? Linnaeus. W(‘ must 
therefore consider Musca vihrnns the gc'notype of Mo.sillus 
Latreille, 1804. This aceei)tance would e.xclude that ge'iius 
from the Ephydridae. Consideration of Moaillm as ante'dating 
(lymnopa may be allowed by dating the former from an bSOo 
reference,® where Musca arcuatus Latreille is the included sjk'- 
cies. Study of the descriptions of the 1804 and 1805 I'eferences 
shows that, although identical they are very different from that 
of his ‘‘Slouches vibrantes, ” and from the .same division men- 
tionetl in the Dictionnaire.® The latter evidently refei's to the 
hies allied to the pre.sent Seioptera lyibrans. It will be s('('n fi’om 
the above analysis that the name d/o.sd/a.s' had better be discard- 
ed, at least for this genus. 
Gymnopa tibialis Cre.sson (Plate XX, figures 1, 4, and .j.) 
lOK). M osillus Ubidlir Cresmn, Ent. News, xxvii, 149. 
This name was proposed foi' our Amei'ican species, which 
differs in many respects from specimens of the Eui'oix'an sub- 
sultans examined. Most noticeably is this so in having tlu' 
frontal triangle densely granulosc' or scabrous m'ai' tlu' oc('lli, 
and the tiluae tawii}', not black. 
Desertptiou. — (f, 9. black; third antennal joint soinetiines, tibiae ('xcei)t 
middle of hind pair, tarsi except ajjices, tawny. Halteres white. Wings 
hyaline with milky tinge; veins yellow. 
Shining to i)olished with faint metallit! refiections. (dieeks and abdomen 
smooth and polished. Frontal triangle setulose, densely and fiiu'b' punctate, 
esj^ecially near the anterior ocellus; frontali.a smooth and subopaciue. I'acial 
tubercle in profile, conical (fig. 1). Parafacialia, but not cheeks, foveae, the 
papillose facialia, and antennae somewhat, silvery. Mesonotum d('ns('ly 
scaibrous and sparingly light pruinose, which appt'ars mor(' dc'nsi' as two 
anterior median vittae and irregular lati'ral areas. Sculcllum scabrous and 
setulose, the margin with several stout, short bristles bt'sidc's tin' usual lour. 
Second abdominal segment tlu* longc'st, with a depressed triangular arc'a in 
the middle' of the dorsum liasally; filth se'gnu'nt triangular, truncate', with .-t 
'* Hist. Xat. Crust, et Ins., m, l.jS, 1S()2. 
•’ Hist.. .Xat. ('rust, et Ins., .\i\', .‘ISU, ISO.) (.An. xm). 
'Cxv, 129, iso:;. 
TK.-VN.S. .\M. ENT. Soe’., XI.VII. 
