MOLLUSCS, VERMES AND HYDROZOA 



U. complanatus, Fig. 184, is the widely distributed species, found in 

 ponds and streams. The valves vary in form but are usually oblong-ovate, 

 rather compressed and posteriorally the broader. The umbones are mostly 

 eroded and have an obtuse 

 ridge to the posterior tip. 

 The hinge has a single 

 coarsely-striated cardinal 

 tooth in the right and two 

 nearly equal teeth in the 

 left valves. The color is 

 usually a yellowish-green in 

 the younger and brownish- 

 green in the older shells, tig. li^. Uma complanatus. Adult. 



and is dark green posteriorally at the hinge. The lines of growth are faintly 

 and evenly marked. The valves have an iridescent violet pearly nacre 

 on the inner side with a delicate pink and salmon-yellow edge, and are 3 

 inches long, 2 inches broad and i inch thick at the unbones. The animal 

 is yellowish-and greyish-white with a long foot. It occurs in almost every 

 stream and river on the Atlantic slope and is a most active mussel, often 

 moving several inches in a day. A good and desirable scavenger in the 

 aquarium where it will often survive for years. 



Lampsilis. This genus of the Unionidse was formerly classed with 



the Unios and embraces most of the Eastern and Middle States species. 



L. radiatum. Fig. 185, has broad oblong-ovate beautifully striated dull 



greenish-yellow valves showing distinct lines of growth and overlaid with 



green and brown rays radiating from the edges of the umbones. It is one 



of the handsomest fresh- 

 water mussels. The interior 

 of the valves shows a deli- 

 cate iridescent nacre and 

 the hinge has erect cardinal 

 teeth strengthened by a rib 

 behind the anterior mus- 

 cular impression. It grows 

 to a length of 3 inches, 

 nearly 2 inches broad and 

 1% mch thick; and may be found in most large ponds and streams, but 

 is not as long-lived in the aquarium as the foregoing. 



L. ochraceus. Fig. 186, is variable in form but usually has thin, trans- 

 versely oblong, sub-ovate, translucent, inflated and widely gaping valves, 

 with elevated and almost touching umbones. The color is yellowish- 



Z42 



FIG. 185. Lampsilis radiatum. Adult. 



