44 CATALOGUE OF 



CIIOMERIAN. 

 NORFOLK, EAST. EN. 



Sherringham [M. P. G.] ; West Runton [A. S. K.] [M. P. G.]. 



PLIOCENE. 



NOKFOLK, EAST. EN. 



Bramerton Common [N. M.]. 



This is a very widely distributed species on the Continent and 

 is met with from Iceland [F. H. Sikes Coll.] and Lappland 

 [Odhner Coll.] to Sicily, and from France to Lake Baikal. From 

 this last locality it has been received under several names including 

 that of P. dubium, Lindholra (95, p. 85). 



On the other hand authentic fossil records are at present scarce. 

 It has been recorded from the Holocene of Denmark [Johansen 

 (85, p. 9)]; seen from the Pleistocene (Campinien) of Soignes, 

 Belgium [Mus. Hist. Nat. Brussels] ; and mentioned as met with 

 in the Pleistocene (Mosbacher Sand) of Mauer (near Heidelberg) 

 [Geyer (69, p. 96)]. 



It is possible that the P. capellinii, Saeco (151, p. 437), from 

 the Pliocene of Piedmont may be a flattened form of this species. 



4. Pisidium nitidum, Jenyns. 

 [Pis. I, f. 9 ; III, f. 6 ; XIX.] 



1832. Pisidium nitidum, nobis : Jeuyns, Trans. Camb. Phil. Soc. iv, 



p. 304, pi. xx, f . 7 & 8. 



1843. Cyclas nitida, Jenyns : Hanley, Cat. Rec. Bivalve Shells, p. 90.' 

 1854. Pisidium incertum, Nob. : Normand, Coup d'oeil Cyclades Nord, 



p. 6. [Quotes Jenyns sp. & fig. as synonym !] 



Pisum nitidum, Jenyns : Deshayes, Cat. Conch. Brit. Mus. ii, 



p. 277. 



18o8. Musculium nitidum ^ Jenyns : Adams, Gen. Rec. Moll, ii, p. 451. 

 1859. ? Pisidium pusillum, var. obtusalis : Jeffreys, Ann. & Mag. Nat. 



Hist, m, iii, p. 37 : id., Brit. Couch, i, 1862, p. 24. 



1873. ? Pisidium pileus, n. sp. : Clessin, Correspond. -Bl. zool.-min. Ver. 



Regensburg, xxvii, p. 150. 



Pisidium fossarinum, 8. acuminatum, Clessin : Clessin in Wester- 



lund, Fauna Moll. Svecias, p. 545. [C/". specimens in Norman 

 Coll., B.M. 98. 5. 26 : 22253-54.] 



1874. Pisidium sphariiforme, n. sp. : Clessin in Fedchenko, Tzvyest. imp. 



Obshchest. Lyubit. Estestvoz. Antrop. I Etnogr. Moskva, xi, 

 yuip. 1 ? p. 38, pi. iii, f. 33. 



1909. Pisidium granum, n. sp. : Liudholm in Korotneff, Wissensch. 

 Ergebn. Zool. Exped. Baikal-See, iv, p. 87. 



This is a somewhat polymorphic form and its extreme variations 

 have been frequently mistaken for small P. casertanum, P. person- 

 atum or P. pusillum. 



Jenyns, who was the first to separate it as a species, thus describes 

 it (83, p. 304) : 



