MYTILUS. 139 
Movtilus lithophagus. 
The box thus marked in the Linnean cabinet contains two 
species, both of them included by Lamarck in his Modiola 
lithophaga. ‘The Indian form (Chemn. Conch. Cab. vol. viii. 
pl. 72, f. 729) has been lately distinguished as Lithodomus teres, 
the name lithophagus being retained for the common Mediterra- 
nean Lithodomus (Sowerby, Genera Shells, Lith. dactylus). 
The “extus picea” “ oblique striata” of the ‘Museum Ul- 
rice’ is adverse to this arrangement of nomenclature ; but the 
circumstance that not one of the cited figures represents the 
narrow Indian variety, favours it. Lister’s engraving (37 was 
clearly a misprint for 39, and is thus altered in the revised copy) 
represents a fossil; Bonanni, Argenville, Gualtier, &c. the EKu- 
ropean shell. The expressions ‘“ suavissimus” and “ dentes 
cardinis nulli” have been added to the description in the re- 
vised copy of the ‘Systema,’ and “ Act. Paris. ext. 5, p. 467, 
t. 478” referred to as an additional synonym. 
SMiyptilus vugosus. 
The Saxicava rugosa of authors is not present in the Lin- 
nean collection. The shells contained in the box thus marked 
in the cabinet are worn, full-aged specimens of Sazxicava are- 
tica (Turt. Dithyra Brit. pl. 2, £18, as Hiatella oblonga) and 
perfectly agree with their published description. Lister’s en- 
graving is not unlike them; Gualtier’s figure, on the contrary, 
is that of a young Unio; so that the attached ? was probably 
transposed by accident. Linneus appears to have found out 
the identity of the species with his Mya arctica; for in his MS. 
he has almost erased its description, in his endeavour to con- 
vert the species into a true Mytilus ( Magellanicus ). 
Movtilus bilocularis, 
Even in the tenth edition of the ‘Systema’ the specimen 
subsequently described in the ‘ Museum Ulrice’ was pointed 
