PISIDIUM. 11^ 



Pisidium ferrugineum.* 



Pisldium fernigineum. Prime, Proc. Bost. Soc. Nat. Hist. iv. 162 (1852); Bost. Jonni. 

 Nat. Hist. vi. 362, pi. 12, figs. 8, 9, 10; Ann. N. Y. Lye. vii. 98. 



Sliell small, rounded-oval, globose, slightly inequilateral ; anterior 

 side somewhat produced ; margins rounded ; beaks 

 tubercular at apex, very distant ; surface smooth ; '" 



epidermis light yellow ; hinge-margin rounded ; car- 

 dinal teeth large, separate, anterior tooth more prom- 

 inent ; lateral teeth distinct. Length, seventeen hun- 

 dredths of an inch ; breadth, thirteen hundredths 

 of an inch ; width, eleven hundredths of an inch. ^' Eniafgoa.""' 



North America, in the States of Maine and New 



York. Fig. 424. 



Remarkable for the elevation of its beaks, which stand 

 forth on the upper portion of the shell in the shape of 

 large tu)3ercles, which are generally coated with some ^'nZZf' 

 dark ferruginous substance. It differs from P. abditum 

 in being smaller, more inflated, not so elongated, and more equilat- 

 eral. 



One of our most common species, found usually in company with 

 P. variabile and P. ventricosum QPrime'). 



Pisidium abditum.* 



Pisidium abditum, Haldeman, Proc. Acad. Nat. Sc. Phila i. 53 (1841). 



CyrJas minor, C. B. Adams, Bost. Proc. i. 48 (1841). 



Pisidium tenellum, Gould, Agassiz's Lake Superior 245, (1848). 



Pisidium obscurum, Prime, Bost. Proc. iv. 161 (1851). 



Pisidium rubellum. Prime, loc. sup. cit. iv. 163 (1851). 



Pisidium minus, Stimpson, Moll. New England, 16 (1851). 



Pisidium Kurtzi, Prime, Bost. Proc. iv. 162 (1851). 



Pisidium zonatum, Prime, loc. sup. cit. iv. 162 (1851). 



Pisidium regulare, Prime, Bost. Journ. vi. 363 (1852), pi. 12, figs. 11, 12. 



Pisidium notatum. Prime, loc. sup. cit. vi. 365 (1852), pi. 12, figs. 20-22. 



Pisidium arcuatiim. Prime, loc. sup. cit. vi. 364 (1852), pi. 12, figs. 14-16. 



Pisum abditum, Deshayes, Brit. Mus. Cat. 282 (1854). 



Pisum minus, Deshayes, loc. sup. cit. 281 (1854). 



Pisidium resartum, Ingalls, in litt. 1855. 



Pisidium rubrum, Lewis, in litt. 1855. 



Pisidium plenum, Lewis, in litt. 1855. 



Muscutium abditum, Adams, Kec. Gen. ii. 451 (1858). 



Musculium minus, Adams, loc. sup. cit. ii. 451 (1858). 



Musculium rubellum, Ada.ms, loc. sup. cit. ii. 452 (1858). 



* See note, page 107. 

 8 



