﻿494 AI.ASMIDOXTA 



.Animal having the iiincr qiils w idcr lliaii the outer throui;:!!- 

 out ; palpi lony; ; marsu])iuni loose and llahliv, and having- ova 

 scattered throuj^hout it in the onlv gravid s|)ccimen seen. 



Al.ASMIDONTA UNDULATA (Say). 



Shell elliptical or suhrhomboid. subinflated, solid, inequi- 

 lateral, with full, hi^h beaks, whose scul])turc consists of very 

 strouiT ridges that run i)arallel with the grow tli lines ; in front 

 of and behind them there arc often raised, radial threads : pos- 

 terior ridge well develoi)cd, rounded, ending; behind g^enerally 

 below the median line; surface with uneven growth lines; 

 epidermis yellowish-green to dark brown or blackish, painted 

 with wide and narrow rays, which are in old shells visible only 

 by transmitted light, usually shining; left valve with a strong 

 tooth under the beak and a small one in front ; right valve with 

 one irregular tooth in front of the beak ; laterals almost want- 

 ing, blurred ; anterior scars impressed ; beak cavities deep, 

 compressed : nacre bluish-white. pur])lish or salmon, thickened 

 in front. 



Length ys- height 44, diam. 30 mm. 



IvCngth 70, height 47, diam. 32 mm. 



Length 50, height 30. diam. 19 mm. 



Lower St. Lawrence drainage ; southward to North Caro- 

 lina. 



Type locality, Delaware and Schuylkill Rivers. 

 Monodonta undiilota Say, Nich. Enc, 1817, pi. iii, fig. 3. 

 Alasmidonta undiilaia Say, Jl. Acad. N. Sci. Phila.. L 1818, p. 



460. — Simpson, Syn., 1900. p. 667. 

 Alasmodonta ttndulata Say, Nich. Enc, 1810. pi. m. fig. 3. 

 Alasuiodon undnlota v^wainson, Tr. on Mai., 1840, p. 288. fig. 



6t. — Gould. Tnv. Mass., 1841, p. T15. fig. 76. — Dk Kay, Zool. 



of N. Y.. Pt. 5, 1843. p. 198. pi. XV. fig. 227. 

 Margarita (Marcaritana) vndulata I<k\. Svn.. T83r). p. 44: 



T838, p. 27. 

 Unio undiilafa Hani.ky. Test. Moll., 1842, p. 211. 

 Mari:aritana undulata Kustf.r, Conch. Cab. Unio, 1862, p. 



208, pi. xcix, fig. 4. — Gould. Tnv. Mass.. 1870, p. 176. fig. 



478. — Hartmax and ATicttrnkr. Conch. Cest.. 1874. p. 02, 



fig. T90. 



