42 



NEW UNIONID.E OF THE 



Unio vektricosus Barnes.* PI. 30, fig. 107. 



Soft parts. — BrawMal uterus occupies the posterior portion of the outer branchiae, 

 like cariosus Say, and is blackish on the lower border. There were no ova in the 

 uterus, but the enlargement of the branchial ovisacks gave the appearance of their 

 having been recently extruded. BrancJdce large, semicircular, inner ones much the 

 larger, united the whole length of the abdominal sack. Paljii small, thin, suboval, 

 united nearly half way down the posterior edges. Mantle rather thin, very much 

 thickened and enlarged along the lower edges, blackish mottled on the posterior basal 

 edges, which protruded largely, extending a large, fleshy, flexible process, furnished 

 with several acute points. Branchial opening large, with numerous, rather large, 

 brownish mottled papilliB. Anal opening large, with very numerous, small, brownish 

 mottled papillte on the edges. Super-anal opening very long, colored brown on the 

 inner edges and united at the lower part. Color of the mass whitish. 



Remarks. — I am indebted to E. Billings, Esq., of the Canada Geological Survey, 

 for this and many other species in a living state, taken in the St. Lawrence, at 

 Montreal. The drawing made by myself, when the animal had thrown out to its 

 utmost extent those parts which it extrudes when feeding, is well represented by the 

 artist on stone. The shell will be recognised to be a mere hasty, but correct outline 

 of the female form. The fleshy process, as represented, gives a good idea of the 

 extensile and retractile power of these muscular organs. The whole form can be 

 changed at the will of the animal, and all the parts now visible may be drawn within 

 the valves at the slightest alarm. 



MaRGAKITANA llARGAEITIFERA.f PI. 29, fig. 104. 



Mija margaritifera Lin. 



Margaritanu fiuviatilis Schum. 



Unio elongata Lam. 



Alasmodonta falcata Gould. J 



Soft parts. — Branchial uterus . No ova were found, either in the branchiae or 



the abdominal sack, of quite a large number most kindly sent to me alive by Dr. 

 Shurtleffl of Westfield, Mass. It is hardly likely that all could have been males, yet 

 they had that appearance. § Branchice very large, curved below, oblique behind and 

 somewhat truncate before, inner ones much the larger, dark lead color passing into 

 black behind and into dirty brown before, free nearly the whole length c^ the 



* Am. Jour. Sci., Vol. 6. 

 t Synopsis Fam. Naiades, 3d ed. p. 43. 

 t For further synonyomy and authors see my " Synopsis." 



?. It is much to be regretted that, in giving this description, I am unable to present the fori 

 the branchial uterus. 



and position of 



