﻿LAMPSILIS 183 



Thinner and more evenly elliptical, with a less developed 

 marsupial swelling than alata, and it has much lighter colored 

 nacre. It is more elongated, is duller colored and has a less 

 developed wing than Iceinssinia. 



Ortmann, (Mem. Car. Mus., IV, 191 1, p. 334), has made this 

 species the type of a new genus, Paraptera, based on the shape 

 of the glochidia, which are of the usual Lampsiline type, with- 

 out spines and very small. 



IvAMPSiLis r..TiVissiMA (Lea). 



Shell, without the wings, nearly evenly elliptical, a little 

 wider behind with a decided posterior and anterior basal gap, 

 thin, subcompressed, strongly alate, having a very high, trian- 

 gular posterior wing that is often flexed at the top, and a 

 smaller anterior wing; beaks subcompressed, not high, with a 

 few nodulous, broken, slightly-looped ridges ; surface with nu- 

 merous irregular growth lines and sculptured in fine specimens 

 with delicate radiating lirse, smoky-olive, lighter at the beaks, 

 the rest bands dark, brilliantly polished ; left valve with one or 

 two feeble, compressed pseudocardinals and two remote, deli- 

 cate laterals ; right valve with one pseudocardinal, sometimes a 

 faint one above it, and a high, truncated lateral ; beak cavities 

 shallow, with an irregular row of shallow scars ; adductor scars 

 large and shallow ; nacre purplish. The male and female shells 

 are so near alike that it is often ditificult to separate them. The 

 male shell is generally slightly rhomboid behind and the female 

 is a very little fuller along the base than the male. 



Length 120, height without measuring the wing 76, diam. 

 37 mm. The wing when well preserved in adult shells is about 

 25 mm. in height. 



Mississippi drainage generally; eastern Texas; southern 

 Michigan ; western New York. 



Type locality, Ohio. 

 Symhhynota Icevissima Lea, Tr. Am. Phil. Soc, III, 1830, p. 



"444, pi. xiir, fig. 23 ; Obs. I, 1834, p. 58, pl- xm, fig- 23. 

 Unio Icevissima Deshayes, An. sans Vert., 2d ed.. VI, 1835, p. 

 558. 



