556 UNIO 
Unio mauritanicus Bourcuicnat, Moll. Nouv., 1868, p. 317, 
pl. xiv, figs. 1-5.—Kosext, Icon., I, new ser., 1886, p. 5, 
pl. xxxiu, fig. 230. 
Umio ksibianus Mousson, Mal. Blatt., XXI, 1873, p. 156; 
Jahrb. Deuts. Mal. Ges., I, 1874, p. 104, pl. v, fig. 6—Ko- 
BEWT Jicon,, 1V,,new ser.;.1870,. p65, pls cxixernosemnse! 
Umio jolyi Kove t, Icon., new ser., II, 1886, p. 22, pl. x1, fig. 
250. : 
Unio maccarthyanus Koper, Icon., new ser., II, 1886, p. 5, 
DISK aie 226) 
Unio letourneaurt Koper, Icon., new ser., II, 1886, p. 3, pl. 
KOKI eae 
Unio -lycicus RovuLE, Lcon., 1stistip.;.1895, p16, pl ie, me. 
Considering the abundance of specimens of this species and 
its wide distribution, I do not think it a remarkably variable 
form. It is usually decidedly rhomboid, is subcompressed or 
convex but rarely subinflated. The lighter colored specimens, 
which are generally young, quite commonly show rays and 
there is sometimes a broad ray that covers the whole posterior 
end. The checker board pattern of beak sculpture is charac- 
teristic, sometimes spreading well out on the disk. I have seen 
no forms that seem to be worthy of varietal rank. 
Lamarck refers this in the Animaux sans Vertebres first to 
his Systeme An. sans Vert., published in 1801, and thirdly to 
Draparnaud (Hist. Moll. Fr., 1806). Draparnaud published 
this species under the name Unio littoralis without a figure in 
the Tableau Mollusques de France, 1801, which appeared, ac- 
cording to Moquin-Tandon, about July 1 of that year. I do 
not know: which has priority, but Lamarck refers to a charac- 
teristic figure in the Encyclopedia Methodique (1797), thus 
fixing the species without a doubt, and as he is most generally 
considered its author I shall credit it to him. 
Hannibal, (Proc. Mal.-Soc. London; xX, 1912;*p.124)), ads 
made this species the type of a new genus, Migranajas, based 
on the characters of the beak sculpture and the hinge-teeth. 
