NO. 1205. SYNOPSIS OF THE NAIADES SIMP SOX. 525 



ridges; hinge teeth heavy, laterals dab-shaped and truncated poste- 

 riorly: post-basal swelling of the female, distinct and often rather 

 abrupt, sometimes somewhat irregularly radially ridged, the shell of 

 this part being rather thin. 



Animal with mantle fringed below, maculate on the border, which is 

 greatly thickened at the post-basal part in the female and developed 

 into a flap, with a distinct, toothed ridge inside; marsupium occupying 

 the posterior part of the outer branchiaj in numerous distinctly marked 

 ovisacs: inner gills free from abdominal sac in part. 



(Group of Micromya fabalis.) 



Shell small, with faint undulate rays, inflated area of female scarcely 

 radiately striated. 



t MICROMYA FABALIS Lea. 



* Unto fabalis, 1 LEA,Tr. Am. Phil. Soc., IV, 1831, p. 86, pi. x, tig. 6; *Oba., 1, 1834, p. 



96, pi. x, fig. 16.* FERUSSAC, Guer. Mag., 1835, p. 27.* HAXLEY, Test. Moll., 

 1842, p. 196; *Biv. Shells, 1843, p. 196. * CATLUW ami REEVE, Couch. Norn., 

 1845, p. 59; *H. ami A. ADAMS, Gen. Rec. Moll., II, 1;V7, p. 494. * CHEXT, 

 111. Conch., 1858, pi. vm, figs. 1, la, lb. * SOWERBY, Conch. Icon., XVI, 1866, 

 pi. xxxvi, fig. 196. 



* Marcjarita ( Unto) fabalis EEA, Syn., 1836, p. 28 ; 1838, p. 20. 



* Margaron ( Unio) fabalis LEA, Syn., 1852, p. 31 ; 1870, p. 49. 

 Unio capillus SAY, Transylvania Journ., IV, 1831, p. 528. 



* Unio lapillus SAY. Am. Conch., V, 1832, pi. XLI ; VI, 1834, No. 49. *CONRAD, New, 



K. W. Shells, 1834, p. 70. ; * Monog.,VI, 1836, p. 54, pi. xxix, fig. 12.* CHEXU, 

 Bib. Conch., 1st ser. Ill, 1845, p. 52, pi. xiv, figs. 1, la, 16. *KUSTER, Conch. 

 Cab., 1848, p. 53, pi. xi, fig. 3.* CONRAD, Pr. Ac. N. Sci. Phila., VI, 1853, p. 

 251. *B. H. WRIGHT, Check List, 1888. * PJETEL, Conch. Sam., Ill, 1890, p. 

 156. 



Ohio River drainage ; Rouge River, near Detroit, Michigan ; New York. 

 (Group of Micromya ca'lata.) 



Shell triangular ovate, with alow, rounded posterior ridge; male and 

 female shells distinctly wrinkled behind. 



t MICROMYA C^LATA Conrad. 



*Unio ca'latus CONRAD, Am. Jl. Sci. and Arts, XXV, 1834, p. 338, pi. i, fig. 1; 

 New, F. W. Shells, 1834, p. 29, pi. in, fig. 4, p. 68.* FERUSSAC, Guer. Mag., 

 1835, p. 29. *MOLLER, Syn. Nov. Gen., 1836, p. 199. *HANLEY, Test. Moll., 

 1842, p. 175; *Biv. Shells, 1843, p. 175. * CHEXU, Bib. Conch., 1st ser., Ill, 

 1845, p. 16, pi. in, fig. 3. *CATLOW and REEVE, Conch. Nom., 1845, p. 56. 

 *H. and A. ADAMS, Gen. Rec. Moll., II, 1857, p. 497. * REEVE, Conch. 



'According to Scudder the volume of the Transactions containing this species 

 appeared in the latter part of 1831, and was acknowedged by correspondents as 

 received that year. Say published his U. capillus in the Transylvania Journal for 

 December, 1831, and in the American Conchlogy changed it to lapillus. It is proba- 

 ble that Lea's name was published first. 



