ORTMANN: monograph of the naiades of PENNSYLVANIA. 3 



Soft parts and (/lochidia (See Ortniann, 1912, p. 230, fig. 1; and 19136, p. 89). 

 In the American form, the glochidia have not yet been observed. The fine teeth 

 on the lower margin are present only in fully mature glochidia. 



The breeding season in Pennsylvania occurs in the period from June to August 

 (Conner, 1909, p. 112); in Europe it occurs from the middle of July to August 

 (Harms, 1907, p. 818; Carl, 1910, p. 16). 



Remarks: There is no possibility of mistaking this species, for it is sharply 

 characterized by size (being the largest shell of the Atlantic-drainage), shape, color, 

 hinge, and by its peculiar station. Compared with the same species from other 

 localities, the Pennsylvanian specimens are remarkable for their size, being the 

 largest ever recorded. I cannot see any differences between them and specimens 

 from New England and Newfoundland. European shells likewise perfectly agree 

 with them. Specimens from the Pacific slope are all considerably smaller and 

 comparatively thinner, and the color of the nacre inclines more toward purphsh 

 tints. There are also slight differences in the hinge. This western form has been 

 distinguished as a variety {falcata Gould) . 



Localities represented in the Carnegie Museum: ^ 



Locust Creek, Tamaqua; Cold Run, Hecla; Indian Run, Rene Mont; all in Schu.ylkill Co., Pennsylvania. 

 Westfield, Hampden Co. (Hartman collection); Amherst, Hampshire Co., Massachusetts (Holland 



collection). 

 Amj' Brook, Honniker, Merrimack Co., New Hampsliire (G. H. Clapp). 

 Cape Elizabeth, Cumberland Co. (G. H. Woods); Aroostook River, Caribou, and Little ^Ladaw•aska 



River, New Sweden, Aroostook Co., Maine (0. 0. Nylander). 

 South West River, Belvoir Bay (Hare Bay), Newfoundland (G. H. Clapp). 



From Europe (all received from W. Israel) : 

 Perl Bach, Postfelden near Falkenstein, and Perlbach, Rehau above Hof, Bavaria; Goernitzbach, Ocl- 



snitz. Saxony; Aumabach, Rohna, Saxe- Weimar; Steinach, Sonneberg, Saxe- Weimar; Ulfenbach, 



Affolterbach, Hesse, Germany. 



From the Pacific slope (var. falcata Gould) : 

 Long Valley, Lake Co., California (Hartman collection); Chehalis River, Porter, Chehalis Co. (H. 



Hannibal); Seattle (P. B. Randoliih), and Ravenna Park, Seattle, King Co., Washington (H. 



Hannibal). 



Distribution and Ecology in Pennsylvania (See fig. 1): This species has been 

 recorded by Lea from Crum Creek, Delaware Co., and by Hartman & Michener 

 from White Clay Creek, Chester Co. Lea also says that it goes southward only 

 as far as middle Pennsylvania. I have expressed (19096) my doubts as to the 

 correctness of these two localities, and must maintain them most emphatically. 

 In White Clay Creek I have collected myself, and found only the common fauna 

 of the Atlantic streams, and Margaritana is not found where this is present, accord- 

 ing to my experience. 



' When not otherwise indicated, the specimens have been collected by myself. 



