r 



VARIATION IN NACREOUS COLOR OI^ NAIADES 213 



a deep purple color. Utterback, (16), found that the nacre of 

 Elliptio was darker in upstreams sections fading out toward the 

 mouth confirming Wilson and Clark's observation. He addition- 

 ally points out that of Quadrula verrucosa that the pink nacred 

 shells are confined to southern Missouri; of Pleurohema obHquwm 

 catillus that in the Gasconade it has a white nacre, while in the 

 Osage River it is pink. Wilson and Clark further, (18), the color 

 of Anodonta grandis is in ^2 tne cases dark purple, the other half 

 creamy white. There may be added a curious observation of 

 Israels on Unto crassus, that the epidermis of females were 

 usually of a gray color, while that of the males were red. 



Following the clues given in the foregoing, effort will be made 

 in this paper to throw light on the following problems connected 

 with the color of nacre in species of Naiades dealt with, viz; 



I. In those species commonly assigned more than one characteristic 

 nacre color, to determine as far as possible the relative prevalance of 

 each color in all the shells as a whole, and the difference hetvoeen L. 

 Erie and Upper Ohio shells in this regard. 



II. To determine whether any change in nacreous color takes 

 place going down stream, both in the rivers and their tributaries, 

 and to learn whether in any of the species, a particular shade of the 

 described nacre color is pecuHar to the bady of water concerned. 



III. To associate as far as possible certain shades of the described 

 nacre color with the sex of the animal in each oj the species dealt with. 



II.— List of Species Used. 



LAKE ERIE UPPER OHIO DRAINAGE 



1. Fusconaja fiava parvula ,Grier. Fusconaja flava, Raf. 



2. Amblema plicata, Say. Amblema costata, Raf. 



4. Pleurobema obliquum pauperculum, Pleurobema obliquum coccineum, 



Simpson. Con. 



J. Elliptio dilatalus sterkii, Grier. Elliptio dilatatus, Raf. 



5. Syphynota costata eriganensis, Grier Symphynota costata, Raf. 



6. Anodonta grandis footiana. Lea. Anodonta grandis, Say. 



7. Paraptera alata, Say. Paraptera alata, Say. 



7. Paraptera fragilis, Raf. Paraptera fragilis, Raf. 



8. Proptera alata. Say. Proptera alata, Say. 



g. Anodontoides ferrus-subcylind. Lea. Anodontoides ferrussacianus Leo. 



10 Eurynia recta, Lam. Eurynia recta latissima, Raf. 



11. Lampsilis luteola rosacea, Dekay. Lampsilis luteola. Lam. 



12. Lampsilis ovata canadensis. Lea. Lampsilis ovata ventricosa. Lam. 



The accompanying map and list of localities showing the collect- 

 ing stations will give some idea of their distribution in the Upper 



