44 MUSSEL FAUNA OF THE KANKAKEE BASIN. 



found only in the lower stretches of the Kankakee. The first we 

 saw were in the clammer's pile at Momence, where it was fairly 

 common. A few were found in the mouth of the Kankakee. 



9. Quadndaundulata {Bwmes). TAree-nc^^e.— Two closely related 

 shells, Q. undnlata and Q. pUcata, are known to the shell trade as 

 "three-ridge" and "blue-point," both names being applied indis- 

 criminately to either species. The extreme forms of these two spe- 

 cies are well marked and easily recognizable, and where this is the 

 case it is better to apply the term " three-ridge " to Q. undulata and 

 "blue-point" to the other shell. Generally, one does not find well- 

 marked examples of both species in the same stream; where the well- 

 marked flatter form {Q. undulata) is conmion, the fuller form 

 {Q. plicata) is usually, if not always, absent. All the shells in the 

 Feeder Canal, at Fort Wayne, Ind., seem to be Q. undulata, and 

 all noted from the Illinois River seem to be Q. plicata. The shells 

 of White River, Ind., seem to be intermediate. 



Q. plicata is a fairly valuable button shell and is usually regarded 

 among pearl hunters as a fruitful source of pearls. Q. undulata, on 

 account of its thinness, is not quite so valuable as plicata. It is a 

 variable shell and differs considerably in value, according to which 

 of its many forms is encountered. The Q. undulata of the Kankakee 

 is of low value on account of its roughness and the great depth of 

 its furrows, which interfere with cutting and polishing. It was 

 found abundantly and quite large in Fish Lake, as well as through- 

 out the course of the Yellow and Kankakee Rivers, where it was 

 one of the most widely distributed shells. It was fairly common 

 in the Iroquois as well as in the Yellow and Kankakee and was 

 found in Mazon Creek near Gardiner, 111. In the old Kankakee 

 Channel at the Nickel Plate Railroad bridge, also at Davis, Ind., 

 and at Kouts and Burton's camp it was the most abundant shell. 

 At Peterson's camp we found some with a yellow epidermis, and at 

 Tippecanoe Lake (July 28) we obtained three gravid examples. 



10. Pleurohema cesopa {Green) . Bullhead. — The bullhead is a well- 

 known shell among button manufacturers. Its quality and value 

 differ considerably in different rivers, but it is always a rather in- 

 ferior shell on account of its brittleness, and in some of the southern 

 rivers it is so hard and flinty that it breaks the teeth out of the saws 

 and the button cutters do not attempt to cut it at all. Among the 

 clammers of the Cumberland it is known as the " clear profit," as 

 the clammer is the only one who gets anything out of it. 



In the Kankakee this is a very rare shell. The only ones we saw 

 during the entire trip were three in the clammer's pile at Momence 

 and ono at Water Valley. 



11. Plevrohcma dara (Lamarck). — This is a handsome shell, too 

 small to be of any use in the manufacture of buttons. It does not 



