THE NAUTILUS. 101 



terior, low, rounded, scarcely or little elevated over the hinge margin, 

 approximate; surface with moderate to rather coarse, irregular 

 striae, and usually a few coarser lines of growth, shining ; color light 

 yellowish horn, to straw or slightly reddish ; sliell rather thin, some- 

 what translucent ; hinge rather fine, plate narrow ; cardinal teeth 

 well formed, the right one strongly curved, or angular, its posterior 

 part thickened, simple, or grooved, or split in two diverging parts; 

 the left anterior is angular, the posterior is oblique, slightly curved, 

 short to rather long ; lateral teeth rather small, little projecting into 

 the cavity of the mussel, but well formed, the cusps short, pointed; 

 ligament moderate. 



Long. 5, alt. 4.4, diam. 2.5 (New York and some Ohio exs.). 



Long. 5.5, alt. 4.8, diam. 3.4 (large Ohio ex.). 



Habitat : Canaseraga river, N. Y.; Garrettsville, Ohio, in a swamp. 



A lot of good specimens, from the former place, were kindly sent 

 by Mr. Hy. Prime, in 1894, and then regarded as new, yet retained, 

 as it might have proved to be a local form of some other species. 

 Last fall Mr. Streator and tlie writer collected some specimens of 

 exactly the same Pisidium, in a dried up swamp near Garrettsville, 

 Ohio, the mussels living and propagating in the damp muck, under 

 dead leaves, etc. Later on we found that Mr. Streator had collected 

 quite a number during several years previous. 



Our species is well cliaracterized, and can not be mistaken for any 

 other Pisidium. P. roperi, with nearly the same color and surface 

 appearance, is larger, more elongate, much more inflated, its beaks 

 are higher and more voluminous in the adult. I take pleasure in 

 naming the present species after Mr. Geo. J. Streator, an enthusi- 

 astic conchologist, who has, for many years, collected and studied the 

 mollusca of northeastern Ohio. 



SHELLS OF THE MARL-DEPOSITS OF AROOSTOOK COUNTY, MAINE, AS 

 COMPARED WITH THE LIVING FORMS IN THE SAME LOCALITY. 



BY OLOF O. NYLANDER. 



In the part of Aroostook county underlaid by the Aroostook lime- 

 stone of Niagara age, there are many deposits of shell marl. I have 

 only examined two localities : Barren Brook Bog, in Caribou, and 

 Lovely Brook Bog, in Fort Fairfield. 



