00 CATALOGUE OF 



6. Pisidium pusillum (Graelin) Jenyns. 

 [Pis. I, f. 8; III, f. 4; XXI.] 



1791. ? Tellina pusilla : Gmelin in Linne", Syst. Nat. 13th ed , i, p. 3231, 



no. 16. 

 1822. Cyclas pusilla [pars] : Tiirton, Conch. Brit. p. 251, pi. xi, f. 16 & 17 j 



id., Manual, 1831, p. 16, f. 7. 

 Ci/clas fontinalis, Lam, : Nilsson, Hist. Moll. Sveciae, p. 101. 



[Jfcfe Malm, Gotheborgs K. Vet. & Vitt. Samh. Handl. iii, 1855, 



p. 104.] 



1 831 . Cyclas yibba, Leach MS. : .Aider, Trans. Nat. Hist. Soc. Northumbld. 



i, p. 41. (Cf. id. ii, 1838, p. 341.) 



1832. Pisidium pusillum, Gmel. : Jenyns, Trans. Camb. Phil. Soc. iv, 



p. 302, pi. xx, f. 4-6. 



1852. ? Euglesa henslowiana, Leach, Moll. Brit. ?ynop. p. 291. 

 1854. Pisum pusillum. Gmel. : Deshayes, Cat. Conch. Brit, Mus. ii, 



p. 277. 

 1856. Pisidium cazcrtanum, var. y. thennale : Moquin-Tandon, Hist. Nat. 



Moll. France, ii, p. 584. 



1858. Musculium pusillum, Gmel. : Adams, Gen. Rec. Moll, ii, p. 452. 

 1871. Pisidinmmilium, \ai\normandianum, Dupuy : Clessin, Malakozonl. 



Blatt. xviii, p. 194. [Fide specimens from Clessin in Lindholm 



Coll.] 

 1899. Pisidium clessini, n. sp. [pars']: Surbeck, Rev. Suisse Zool. vi, 



p. 482, pi. xii, f. 6-15. 

 1903. Corneocydas (s. s.J pusilla, Gmel. : Dall, Proc. Biol. Soc. Washington, 



xyi, p. 7. 

 1908. Pisidium tornense, n. sp. : OJhner, Naturvv. Untersuch. Sarek- 



gebirges, iv, p. 154, pi. iii, f. 9-13. 



What the Tellina pusilla of Gmelin really was will now never 

 be known ; he describes ib (97, i. p. 3231) as : 



" T. testa ovata Yentricosa. tenui transverse striata, cardine 

 in altera valva edentulo, in altera dente primario duplici." 



He applies the name to a shell described in Schroter's "Geschichte 

 dcr Flussconchylien " (160, p. 194) as " Chama fluviabilis traus- 

 versim striata subovata." The crude figure that accompanies this 

 description (160, pi. iv, f. 7 a & b) represents a very strongly-striate 

 shell that might be Pisidium pulcJieUum, but the shape of which 

 suggests a young P. amnicum. Lister, Turton and others applied 

 the name to the smaller forms of the genus without adequate 

 discrimination and cannot be quoted. 



Jenyns, however, having adopted and applied the name to a well- 

 defined form, his selection must be adhered to. His diagnosis (83, 

 p. 303) is : 



"Testa variabilis, plerumque orbiculato-ovalis, interdum 

 suboblonga margine dorsali recto, vix insequilateralis ; prae- 

 cedenti [P. obtusale] multo magis compressa, marginibus 

 acutis; ssepius extraiiea rubigiue obtecta, qua remota, apparent 



