68 Clark and (J ill cite — Unionidse of Little Arkansas River. 



attractive to the e} T e. Although they lack the iridescence of the best 

 niggerhead material the soft satiny luster is scarcely less attractive, and 

 these shells would make excellent button material. 



•Inst within the nacre of one of the shells are numerous tine whitish, long, 

 crooked tracks, each ending in a small elevation which shows dark be- 

 neath. The dark point proves, on examination, to be a larval Atax 

 which has been coated over with nacre. The peculiar tendency of young 

 Atax to bore entirely through the mantle, crawling along on the nacre 

 and finally becoming covered over with a nacreous deposit, was first 

 noticed during the past summer (1910) by the senior author in »S'. com- 

 planata from the sloughs near Fairport, Iowa. So far, we have observed it 

 in no other species of mussel. It seems improbable that the larvte could 

 ever work their way out again after being thus entombed. They appear 

 to have no other effect upon the nacre than to leave the whitish tracks 

 ending in the low raised point already described, and both of these marks 

 are probably soon covered up and concealed by a new growth of shell. 



4. Anodonta grandis Say. 



FLOATER. 



Fifteen examples, all from near Wichita. These are all mature shells of 

 fairly large size, of the unit us type. None of the shells shows the salmon- 

 colored and diseased nacre usually frequent where parasitic trematodes 

 are common. There are a few pearl-like blisters in some, but as a rule 

 they are free from abnormalities. No. 41 is rather thick and No. 42 has 

 pink nacre. The species has no commercial value. 



5. Tritogonia tuberculata (Barnes). 

 lUVKHORN : PISTOLGRIP. 



Three rather large shells, all from near Wichita. All are moderately 

 elongate and have white nacre. They are of good commercial quality. 



<;. Lampsilis anodontoides (Lea). 



YELLOW SAND8HELL. 



One medium-sized example from near Wichita. This shell is con- 

 siderably deformed and twisted, and the greater part of the epidermis is 

 stained and unusually imbricate. Where it reaches good development, 

 this is the most valuable of the freshwater shells. 



