247 



and without. As in other members of this family from these lakes the optimum 

 habitat does not appear to be here. Many of the shells are coated with heavy 

 deposits of calcareous matter, indicating a chemic condition of the water that is 

 unfavorable to the normal development of the several species. 



Anodonta ferussaciana Lea. One specimen from Turkey Creek ; three speci- 

 mens from Syracuse Lake. 



The resemblance of these shells to the Anodonta mbcylindraeea is very marked 

 indeed. The lake form is lighter both in texture and color than the one speci- 

 men from the creek. 



Anodonta footiana Lea. Three specimens from Syracuse Lake ; one specimen 

 from Turkey Creek. 



The shells submitted are very characteristic of this form, which may not 

 ultimately, be separated from Anodonta lacusti-is Lea. Like its congeners from 

 the same locality the lake form is very pale in color and unusually thin and 

 fragile. A very interesting fact is illustrated in the littoral distribution of this 

 species and Spkarium from the same lake. Those which occur in comparatively 

 deep water are very much thinner and lighter in color than the shore forms. 

 Also, those which are found on the northern shores are thinner and more fragile 

 than those on the southern beach. The reason possibly may lie in the prevail- 

 ing winds, which are from the northeast. The southern beach is also more 

 gravelly than the northern. The conditions of environment then, in this case, 

 favor thicker development of the shell in the forms living on the southern beach ; 

 they need greater powers of resistance, are subjected to rougher conditions of 

 habitat and this finds expression in heavier secretion of nacreous material. The 

 shells which live at the lake's bottom are also beyond the disturbing influence of 

 waves and being deeply imbedded in mud develop to greater size, but with 

 thinner shells. 



Margaritana calceola Lea. A single dead specimen, from Turkey Creek. 



This specimen is a very characteristic one, the deposit of calcareous matter on 

 the inner surfaces of the valves being marked ; this is » pathologic feature, well 

 marked in the type specimens which Dr. Lea studied. This form and Margar- 

 itana deltoidea Lea are synonyms. 



JIargaritana rugosa Barnes. Represented by eight specimens from Turkey 

 Creek, all of which are characteristic. 



Unio coccineus Lea. One specimen, dead, from Turkey Creek. 



The nacre of this shell is quite white, a fact true of the majority of shells 

 which fall under this form, though the type-form was beautifully pink. It is 

 often found in collections labelled TJnia rubiginosus Lea, but is easily separated 



