﻿500 ALASMIDONTA 



Uiiio hctcrodon Lka, Tr. Am. IMiil. Soc, HI, 1830, p. 428, pi. 



viii, lig. 11 ; Obs., 1, 1834, p. 42, pi. viii, tig. 11. — Conrad, 



Monog-., X, 1838, p. 90, pi. xi.ix, tig. 3. — Hani^i^y, Biv. 



Shell.s, 1843, P- i^3> P''- ^^^> %• 4^- — CiiiiNU, 111. Conch., 



1858. pi. XVI, tigs. 2, 2a, 2b. — KusTivU, Conch. Cab., 1861, p. 



192, pi. LXi, tig. 2. — SowiiRUY, Conch. Icon., XVI, 1866, pi. 



XXXV, tig. 184. — Hartman and AIichener, Conch. Cest., 



1874, p. 91, tig. 188. 

 Maro:arHa (Unio) lieterodoii Lica, Syn., 1836, p. 18; 1838, p. 



10. 

 Margaroii (Unio) hcterodon Im\, Syn., 1852, p. 24; 1870, p. 



Alasinidoiita hcterodon Simpson, Syn., 1900, p. 669. 



This shell closely resembles specimens of A. calccolus, but is 

 more delicate and elongated, and is generally more com- 

 pressed, 'i'he pseudocardinals are often (|uite imperfect and 

 generally a little reflexed ; the laterals are lamellar and not 

 perfectly developed, often varying in number. 



Alasmidonta iMVHRSA (Courad). 



Shell rhomboid, considerably inflated, thin, but thicker be- 

 fore, especially at the base, inequilateral ; beaks moderately full, 

 their sculpture not seen ; posterior ridge well developed, end- 

 ing in a rounded point at the base of the shell ; epidermis yel- 

 low ish-olive, clouded with dark brown; rays obsolete or want- 

 ing ; left valve with a three-parted, compressed pseudocardinal ; 

 right valve wnth one compressed pseudocardinal ; laterals dou- 

 ble in the right valve and single in the left ; nacre greenish or 

 wax-colored, dirty white towards the anterior base. 



Length 38, height 24, diam. 18 mm. 



Type locality, Shoal Creek, Xorth .Mabama. 

 Unio diversus 7oNii.\n, Am. Jl. Sci., XXI, 1856, p. 172 (tig. 



in outline). 

 Alasmidonta diiersa Si.Mrsox. Syn.. M)on, p. Uy). 



Conrad has only given a couple of outline figures of this shell 

 and T have never seen it. He states that it bears a remarkable 



