MUSCULIUM. 451 



Terverianum, Dupuy. truncatum, Linsl. 



transversum, Say. 



Genus MUSCULIUM, Link. 



Siphons united as far as their extremities. 



Shell equivalve, thin, usually tumid, sub-oval, inequi- 

 lateral, smooth, or concentrically striated. Hinge with two 

 moderately-diverging teeth in each valve, the front of right, 

 and the hinder of left valve the smallest; lateral teeth 

 elongate, smooth, compressed, of right valve douhle, of 

 left valve simple ; ligament external. 



Syn. Pisum, Miihlf. Pisidium, C. Pfeiff. Pera, Leach. 

 Galileja, Costa. Euglesia, Cordula, Leach. Eupera, Bonrg. 



Ex. M. amnicum, Miiller, pi. Ill, fig. 4. Shell, M. 

 amnicum, fig. 4, a, 4, b. 



In this genus the siphons are short, and united to their 

 ends ; the shells are usually of a green or horn colour, and 

 inhahit streams and ponds, chiefly of temperate countries. 



Species of Musculium. 



abditum, Hahl. dubium, Say. 



abruptum, Hold. duplicatum, Pfeiff. 



altile, Prime. edentulum, Say. 



amnicum, Mull. ferrugineum, Krauss. 



australe, Phil. Heuslowianum, Shepp. 



Bahiense, Spix. Kurtzii, Prime. 



Canariense, Shuttl. lenticulare, Normand. 



casertanum, Poli. Lumstenianum, Forbes. 



Chilense, D'Orb. maculatum, Anton. 



cicer, Prime. minor, Migh. and Adams. 



compressum, Prime. modioliforme, Anton. 



coutortum, Prime. nitidum, Jenyns. 



Creplinii, Dkr. Noveborocense, Prime. 



