THE NAUTILUS. 



67 



ley, in whose honor the species is named, and who has collected 

 specimens of ail stages of growth at various places in the vicinity of 

 Danvers (Nos. 5343, 5355, 5356). 



MUSCULIUM PARVUM, n. sp. 



Siiell small, inequipartite, oblique, medium inflated ; margins gen- 

 erally rounded, or with a slightly marked angle at the junction of 

 the superior margin with the obliquely subtruncate posterior ; anter- 

 ior part of the mussel much smaller than the posterior ; beak some- 

 what anterior, little prominent, broad, calyculate or plain (form 

 aestivalis) ; surface shining, with slight, irregular striae; shell very 

 thin and fragile, transparent to translucent, colorless to pale corn- 

 eous ; hinge very slight, cardinal teeth nearly straight longitudinally, 

 the left posterior above the anterior, which is strongly curved up. 



Soft parts colorless (except for the tan of the liver), also the 

 siphons and mantle edges ; siphons short, very shortly connected 

 when extended, the branchial wide ; foot strongly folded at the sole, 

 when emerging.' 



Long. 4.7, alt. 4, diam. 2.8 mill, (average). 



Habitat : Ohio ; a swamp near Uhrichsville ; also in Stark and 

 Summit Counties, collected by the writer, 1906-'09. Types no. 

 5408 of my collection of Sphieriidae. 



The first specimens were doubtfully ranged under M. securis Pr.; 

 but with the latest ones, and their soft parts, it became evident that 

 they are distinct ; they are smaller, the superior margin is less 

 curved, the posterior is more rounded and more oblique, the surface 

 shining, the shell colorless, while in securh it is generally yellow ; 

 the siphons are mucli shorter and very shortly connected, colorless; 

 in securis they are yellow to orange or salmon or reddish. — M. sphar- 

 icum Anth., so far as known,'^ is larger, the beaks are narrow and 

 much more prominent. 



^This may not be a specific feature. 



2 The two specimens (four loose valves, the third in the lot is a young 

 Spkserium occidentale Pr.), in the T. Prime collection, No. 10 (conf. 1895 cata- 

 logue) and ranged under securis, are hardly suflficient for establishing a species ; 

 the one in the National Museum, No. 11612, is rather difiFerent ; in the Anthony 

 collection no specimens were found. 



