450 



CYRENIDvE. 



are separate and diverging at their ends. The muscular and 

 pallial impressions are indistinct; the latter is provided 

 with a sinus. The species of Sphoerium are all fluviatile, 

 and inhabit, especially, the fresh-water lakes and rivers 

 of cold and temperate regions. They are most numerous 

 in Europe and North America. 



Species of Spharium. 



acuminatum, Prime. 

 albulum, Prime. 

 argentinum, D'Orb. 

 aureum, Prime. 

 bulbosum, Anth. 

 cseruleum, Prime. 

 Capense, Krauss. 

 cardissa, Prime. 

 castaneum, Prime. 

 consobrinum, Ferus. 

 constrictum, Anth. 

 corneum, Linn. 

 dentatum, Hald. 

 detruncatum, Prime. 

 distortum, Prime. 

 dubium, Say. 

 eburneum, Anth. 

 egregium, Say. 

 elegaus, C. B. Adams. 

 elevatum, Hald. 

 emarginatum, Prime. 

 fabale, Prime. 

 flavum, Prime. 

 furcatum, Eajin. 

 giganteum, Prime. 

 gracile, Prime. 

 Indicum, Desk. 

 inornatum, Prime. 

 Jayeuse, Prime. 



lacustre, Midi. 

 maculatum, Morel. 

 mirabile, Prime. 

 modestum, Prime. 

 nitidum, Migh. and Adams. 

 Novoe Zelandise, Desh. 

 orbicularium, Parr. 

 ovale, Stimp. 

 pallidum, Gray. 

 patella, Goidd. 

 partumeium, Say. 

 pellucidum, Prime. 

 pisidioides, Gray. 

 ponderosum, Prime. 

 proximum, Alder. 

 rbomboideum, Say. 

 rivicola, Leach. 

 rosaceum, Prime. 

 Ilyckholtii, Normand. 

 securis, Prime. 

 simile, Say. 

 simplex, Prime. 

 solidum, Normand. 

 spha^rium, Anth. 

 stramineurn, Conr. 

 Steenbuchii, Moll. 

 Steinii, Schmidt. 

 tenue, Prime. 

 tenuistriatum, Prime. 



