BELLINI : FRESHWATER SHELLS OF NAPLES AND NEIGHBOURHOOP. 43 



best specimens; it is smaller and more elongated and the beak less 

 developed and the cardinal tooth shorter. 



In the last few years the European fauna has been enriched by so 

 many named Unioties that Morelet^ jestingly wrote: "elle rivalisera 

 bientot, au moins dans sa nomenclature, avec celle de I'Amerique du 

 Nord." 



Cyrenid^t;. 



(22) Sphaerium corneum L. sp.— "Syst. Nat.," Ed. X., I., p. 



768 {Tellina); Miill., " Verm.Hist.," II., p. 202, nr. 307 {T. rivalis); 

 Phil, "Moll. Sic," 11., p. 30 {Cyclas). In shallow and muddy 

 waters in numerous colonies. 



(23) Pisidium pusillum Gmel. sp.— "Syst. Nat," Ed. XIII., 

 1788, p. 3231 {Tellina); Drap., "Tabl. Moll.," 1801, p. 105, pars 

 {Cyclas fontinalis) ; Phil., "Moll. Sic," II., p. 31 {F. fontinale) ; 

 Costa, O. G., "Fauna Siciliana, Fasc. I., fig. 2 [Galileja tenebrosa). 

 Not common, in fountains in the Botanical Garden, and in the 

 channels of the Sebeto. 



The smallest of the European species of this genus. The genus 

 Galileja, established by the late Prof. Costa on specimens from the 

 Vaccarizzo rivulet, near Gibilmanna, in Sicily, cannot be accepted, 

 because it is founded on the characters of the hinge, which are very 

 variable in species of these genera; and we must also reject the 

 specific name tenebrosa, because the crust covering the individuals 

 examined by him is common to almost all freshwater shells, arising 

 from the confervee that grow in earthy matters on the shell. These 

 cryptogamous plants and the shell grow simultaneously and conse- 

 quently the color is concealed. 



(24) P, casertanum Poll. — "Test. Utr. Sic," I., 1791, p. 65, 

 t. xvi., f. I {Cardiiim) ; Costa, "Catal. test. Sic," p. xxviii., nr. 10 

 ( Cardium). A species localised in a few places. The type of Poli 

 lives in the Royal Park of Caserta; but the form is very variable and 

 rich in numberless synonyms. 



Var. australis Phil.— "Moll. Sic," I., p. 39, t. xxv., f. 11; II., 

 p. 31. More inequilateral and less thick than the type. 



(25) P. amnicum Miiller sp. — "Verm. Hist.," II., p. 205, nr. 389 

 {Tellina) \ Drap., "Tabl. Moll.," p. 186 {Cyclas palustris) ; Drap., 

 "Hist. Moll," p. 131, t. X., i. 17-18 {Cyclas palustris). Common in 

 muddy waters (Sebeto) near aquatic plants. Also from the Sarno 

 (Philippi), but in this locality I have never found it. 



Young specimens are allied to P. casertanum. 



I "Moll. terr. et fluviat. du Portugal," Paris, 1845. p. 108. 



