APPENDIX. 381 



A. a. Sytnphonote Uniones proper (p. 174). 



Unio delphinus (t. 20, f. 44), Gruner, Wieg. Arc. 1841, t. 11,/. 1. 

 —Del. t. 19, /. 3. — Lea, Am. Ph. Tr. 8, t. 17; on U. 3, p. 50. 

 Elongated, with an acutangnlar tin-like projection of the anterior 

 dorsal outline ; very inequilateral, rather thin (the wing extremely 

 fragile), compressed, dark brown, nearly smooth ; ventral edge con- 

 vex, curving obliquely upwards behind ; hinder dorsal edge rectilinear, 

 usually angulated at the extremity ; front extremity subtruncated- 

 cuneiform ; umbonal ridge rendered subangular above by the con- 

 cavity of the anterior slope ; nacre iridescent, silvery white ; car- 

 dinal teeth small, crenulated ; lateral teeth very long and straight, 

 2 (nearly 4 with the fin)... 5. Malacca. 



Unio delphinulus (t. 23, f. 60), Morelet, Test. Novis. 1, p. 31. 

 Elongated-oblong, with a shortish fin-like dorsal wing, inequilateral, 

 very thin, compressed, smooth, olivaceous-yellow or pistachio-green, 

 with a few radiating darker lines on the vicinity of the beaks ; ventral 

 edge curving upwards behind ; wing quite as broad as high, arcuated 

 in front, incurved behind ; anterior slope concave ; anterior extremity 

 briefly sublinguiform ; posterior dorsal corner angular, disposed to 

 alation ; umbones flat ; beaks not raised ; nacre silvery ; teeth 

 laminar, the lateral ones transversely striated. 1-jL (with the fin 1 j) 



A. b. * to *** Non-symphonote nodulous spinous or plicated 



Uniones proper. 



Unio intekmedius (t. 20, f. 28), Conrad, Mon. U. t. 35, /. 2. 

 Transversely subquadrate, very inequilateral, thick, at most subven- 

 tricose, ochraceous - yellow, speckled all over with most crowded 

 minute angular dark green markings, a few of which (on the posterior 

 side) are larger than the rest ; larger anterior moiety nodulous, pos- 

 terior half smooth or with very indistinct incremental plicae ; nodules 

 divergent and linear on the anterior slope, elsewhere tear-shaped ; 

 umbonal ridge preceded by a shallow groove, whose extremity is in- 

 dented : ventral edge arcuated ; posterior side very short, rounded 

 both above and below ; umbones a little prominent, eroded, when 

 young with 2 or 3 anterior pliciform waves ; nacre white or flesh- 

 coloured; teeth solid, the lateral ones rectilinear. 1|...2. N. Caro- 

 lina. 



Unio semigeanosus (t. 20, f. 33), Von dem Busch in Phil. N. C. 1, 

 p. 19, U. t. 1, /. 1, 2, 3. Transversely ovate, inequilateral, solid, 

 ventricose, pitch-brown, not raved, finely and most closely granu- 

 lated in the umbonal region, elsewhere smooth ; ventral edge more 



