NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON. 765 



fPLEUROBEMA CICATRICOSA Say. 



* Unio varicosm LEA, Tr. Am. Phil. Soc., IV, 1829, p. 90, pi. XL, fig. 20; ' * Obs., I, 



1834, p. 100, pi. xi, fig. 20. *HANLEY, Test. Moll., 1842, p. 181; * Biv. Shells, 

 1843, p. 181, pi. xxi, fig. 14. *CATLAW and REEVE, Conch. Nom., 1845, p. 65. 

 * H. and A. ADAMS, Gen. Rec. Moll., II, 1857, p. 496. *CHENU, 111. Conch., 

 1858, pi. xi, figs. 6, 6a, 6&. * B. H. WRIGHT, Check List, 1888. 



* Margarita ( Unio) varicosus LEA, Syn., 1836, p. 17; 1838, p. 16. 

 *Margaron (Unio) varicosus LEA, Syn., 1852, p. 23; 1870, p. 34. 



* Unio cicatricosus SAY, N. Harmony Diss., II, No. 19. 1829, p. 292* SAY, Am. 



Conch., VI, 1834. * FERUSSAC, Guer. Mag., 1835, p. 28. *L. W. SAY, Terr. 

 andFluv. Shells, 1840, p. 5.* CONRAD, Pr. Ac. N. Sci. Phila., VI, 1853, p. 

 246. *KTJSTER, Conch. Cab. Unio, 1861, p. 185, pi. LVIII, fig. 2.* REEVE, 

 Conch. Icon., XVI, 1864, pi. vin, fig. 31; xiu, fig. 50. *B. H. WRIGHT, 

 Check List, 1888.* P^ETEL, Conch. Sam., Ill, 1890, p. 148. 



* Unio cicatricosux var. raricoeus P.ETEL, Conch. Sam., Ill, 1890, p. 148. 



Ohio River; Tennessee; Claiborne, Alabama. The last locality I con- 

 sider doubtful. Lea gives St. Paul, Minnesota, as a habitat, but I do 

 not think it possibly can be. 



The following species are described by Ratinesque, but I ain unable 

 to make them out. 



"Pleurobema mytiloides RAFINKSQUE, Ann. Gen. Sci. Brux., V, 1820, p. 313, pi. 



LXXXII, figs. 8-10. 

 *Pleurobema cuneata RAFINESQUK, Ann. Gen. Sci. Brux., V, 1820, p. 313. 



TETRAGENE^E. 



Male and female shells alike, solid; beak sculpture consisting of 

 coarse, subparallel ridges; beak cavities deep; marsupium filling all 

 four gills, smooth, pad-like. 



Genus QUADRULA (Rafinesque, 182O) Agassiz. 

 (Type, Quadrula metanevra Rafinesque.) 



Quadrula RAFINESQUE, Ann. Gen. Sci. Phys. Brux., 1820, p. 305. 

 Botundaria AGASSIZ, Arch, fur Naturg, 1852, p. 48. 

 Orthonymus AGASSIZ, Arch, fur Naturg, 1852, p. 48. 



Shell triangular, quadrate or rhomboid, solid, inflated, with rather 

 prominent beaks, which are generally sculptured with a few coarse, 

 irregular, subparallel ridges that are inflated where they cross the 

 posterior ridge; posterior ridge ordinarily well developed; base often 

 incurved in old specimens; disks sculptured or smooth; epidermis 

 usually dull colored, dark and rayless, or feebly rayed; hinge plate 



1 1 change Lea's name because Lamarck previously applied the name Unio raricoia 

 to what is, no doubt, Alasmidonta marginata. Mr. T. G. Lea, of Cincinnati, took 

 many specimens of this species, the shells of which he sent to Dr. Lea, and in several 

 of them he has written in pencil "not charged" or "ovaries charged, "'with the 

 date, but neither of them seems to have described the animal. I am somewhat at a 

 loss to know where to placo this curious form. The young are much like thr>sc of 

 Quadrula solida, and do not show the swellings until the third or fourth year, and 

 occasionally the adult shell is nearly smooth. 



