UNIO h 543 
it is sometimes reduced to a few nodules; posterior ridge faint- 
ly narrowly double ending behind in a feeble biangulation 
about on the median line; anterior end rounded, not angled 
above: surface smooth or slightly concentrically grooved, fus- 
cous olivaceous or tawny, sometimes pale yellowish-green or 
greenish-yellow ; the rest periods usually well marked, sub- 
shining: left valve with two subcompressed pseudocardinals 
and two laterals, the lower club-shaped; right valve with one 
pseudocardinal and a vestigial one above it, with one lateral; 
beak cavities not deep: nacre silvyery-white, a little thicker in 
front ; anterior scars deep. 
Length 54, height 29, diam. 23 mm. 
J,ength, 49, height 27, diam. 18 mm. 
Length 79, height 44, diam. 33 mm. 
Assyria. 
Unio mussolianus WusterR, Conch. Cab. Unio, 1851, p. 244. pl. 
LXXXU, fig. 1-—SrmMpson, Syn., 1900, p. 687. 
Unio bourgugnatianus, Lea, Pr. Ac. N. Sci. Phila., VII, 1863, 
Deteo enc MN pcr hilas, VI, 1866, p> 54, pl. xvrt, fig. 
51; Obs. XI, 1867, p. 55. pl. xvii, fig. 51.—-Kosett, Icon., 
new ed., XVIII, 1912, p. 48, pl. piv, fig. 2661. 
Margaron (Unio) bourguignatianus Lea, Syn. 1870, p. 39. 
Umavrasns, Lets Pr Ac. N: Sci. Phila: sViIl, 1863, p. 18979) 
Acad. N. Sci. Phila., VJ, 1866, p. 50, pl. xvi, fig. 47; Obs. 
XI, 1867, p. 54, pl. xvi, fig. 47.—Korext, Icon., new ed., 
AVIII, 1912, p. 47..pl. p11, fig. 2660. 
Margaron (Unio) rasus Lea, Syn., 1870, p. 58. 
Umio mosulensis Lea, Pr. Acad. N. Sci. Phila., VII, 1863, p. 
190; Jl. Acad. N. Sci. Phila., VI, 1866, p. 52, pl. xv, fig. 49: 
Obs. XI, 1867, p. 56, pl. xvn, fig. 40. 
Moargaron (Unie) mosulensis Lea, Syn., 1870, p. 48. 
Margaritana mossulensis Pxtet, Conch. Sam., III, 1890, p. 
173. 
Unio mossulianus Koprir, Tcon., new ed., XVIII, 1912, p. 46, 
pl. piu, fig. 2658. 
I have united a number of nominal species under Kuster’s 
name, which seems to be the oldest. His shell, as figured, ap- 
