NO. 1 soot-ryen: the family mytilidae 19 



The species of Mytilus s. s. are extremely variable in regard to out- 

 line, color, and the thickness of the valves, and consequently many names 

 have been applied to the different forms. 



Mytilus s. s. seems to be of a relatively recent origin, as no records of 

 species which certainly belong to the restricted genus are older than 

 Pliocene. The recent distribution of AI. edulis suggests, hovv^ever, that this 

 species must be rather old. Three or four species may be recognized, viz., 

 Mytilus edulis Linne 1758, with geographical subspecies; Mytilus cali- 

 fornianus Conrad 1837; Mytilus crassitcsta Lischke 1868 (Japan), and 

 perhaps Mytilus giganteus Nordmann 1862. 



The two west American species are generally easily separated : 

 Shell smooth, anterior adductor placed along the anteroven- 



tral margin edulis Linne 



Shell with radial ribs, anterior adductor placed more 



anteriorly calif ornianus Conrad 



Mytilus edulis Linne 1758 

 PI. 1, figs. 1-2; text-figs. 1,2, 10, 11 



Mytilus edulis Linne, Systema Naturae, ed. 10, 1758, p. 705. 

 Syn.: Mytilus pellucidus Pennant 1777. 



Mytilus angustanus Lamarck 1819. 



Mytilus galloprovincialis Lamarck 1819. 



Mytilus planulatus Lamarck 1819. 



Mytilus platensis Orbigny 1846. 



Mytilus trossulus Gould 1850. 



Mytilus glomeratus Gould 1851. 



Mytilus chilensis Hupe 1854. 



Mytilus edulis var. latissimus Carpenter 1857. 



Mytilus grunerianus Reeve 1857. 



Alytilus chiloensis Reeve 1857. 



Mytilus obesus^tewtl'^S^. 



Mytilus fischerianus Tapparone-Canefri 1874. 



Mytilus canaliculus Dall 1876, 1891 {non Martyn 1784). 



Mytilus infumatus Rochebrune et Mabille 1889. 



Mytilus hupeanus Rochebrune et Mabille 1889. 



Mytilus septentrionalis Clessin 1889. 



Mytilus violaceus Clessin 1889 {non Lamarck 1819). 



Mytilus (Eumytilus) patagonicus Jukes-Browne 1905 

 {non Hanley 1843, Orbigny 1846). 



