﻿34 MKKOMYA 



Unio fabalis LrcA, Tr. Am. Phil. Soc. ]\', 1831, ]). 86, pi. x, fig. 

 16; Obs., I, 1834. p. 96, pi. X, fig. 16. — Chenu, 111. Conch., 

 1858, pi. VIII, figs. I. Id, lb. — SowiCKHY, Conch. Icon., XVI, 

 1866, pi. XXXVI, fig. 196. 



Margarita (Unio) fabalis Lea, Syn. 1836. p. 28; 1838, p. 20. 



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



Micromya fabalis Simpson, Syn., 1900, p. 525. 



Bnrynia (Micromya) fabalis Ortmann, Ann. Car. Mus., \'III, 

 1912, p. 339- 



Unio capillus Say. Trans. Journ., IV, 1831, p. 528. 



Unio lapillus Say, Am. Conch., V, 1832, pi. x\a : M. 1834, No. 

 49. — 'Conrad, Monog., VL 1836, p. 54. pi. xxix, fig. 12. — 

 Chenu, Bib. Conch., ist sen III, 1845, p. 52, pi. xiv. figs, i, 

 la, lb. — KusTER, Conch. Cab.. 1848. ]>. 53. pi. xi, fig. 3. 

 A very variable species, in size, form and solidity. Some 



adult male s'hells are scarcely solid or inflated : others are pon- 

 derous and very full. Usually the female shell is smaller and 



more inflated than the male. 



Group of Micromya ccclata. 



Shell triangular ovate, with a low, rounded posterior ridge ; 

 male and female shell distinctly wrinkled behind. 



Micromya c.^.i.ata (Conrad). 



Shell subtriangular to subovate, very solid, convex to in- 

 flated, inequilateral ; beaks high, often subcompressed, turned 

 forward over a small lunule, with feeble, subnodulous sculp- 

 ture ; posterior ridge well developed, narrowly rounded; sur- 

 face with irregular growth lines and well-marked rest periods 

 with strong, corrugated, subradial sculpture on the hinder half 

 of the shell, which is divaricate on the posterior ridge and 

 which sometimes covers the entire shell ; epidermis clouded. 

 dull green and yellowish-green, feebly rayed, rarely uniform 

 dull green; pseudocardinals low, subradial. ragged, two in 

 the left valve, one to three in the right valve ; laterals heavy, 

 double in the left valve, partly double in the right; muscle 

 scars small, impressed; nacre white, silvery', iridescent be- 

 hind, thicker in front. Male shell subovate or subtriangular, 



