MYA. NK. 
slpa truncata. 
An example of the Mya truncata of authors (Wood, Gen. 
Conch. pl. 17, f. 8) is marked for this species in our author’s 
cabinet, and confirmatory references to “ Pet. Gaz. t. 79, f. 12” 
and ‘ List. t. 428” are added in his manuscript. 
spa avenarta. z 
The Mya arenaria of authors (Wood, Gen. Conch. pl. 17, 
f. 3) is marked for this species in the cabinet of Linneus, who, 
in his own copy of the ‘Systema,’ after the word “ excavat,” 
has written “compressa explodit aquam,” and _ substituted 
“adnato” for “ parallelo.” 
spa pictorium. 
Of the two illustrative figures, that of Lister decidedly re- 
presents the Unio pictorwm: Bonanni’s drawing is more doubt- 
ful, and was possibly meant for U. tumidus. The descriptions 
in both the ‘ Fauna Suecica’ and the ‘ Systema’ are brief and 
unsatisfactory, and might suit either species alike. 
More Uniones than one are present in the collection, but 
upon the whole the Unio pictorum of authors (Rossmisl. Iconog. 
Land und Siissw. Moll. f. 196) agrees best with the synonymy 
and description. Upon a specimen of it there is written “ List. 
(Ang.) t. 2, f. 30,” and in the manuscript “ List. t. 147, f. 3” is 
likewise referred to. Both of these references favour the esta- 
blished identification. Our author has remarked, in his copy of 
the ‘ Systema,’ “ Solo cardine differt a Mytilo anatum.” 
Spa margaritifera. 
The Unio margaritiferus of authors (Turton, Dithyra Britan. 
pl. 16, f. 1) is still present in the Linnean collection, and alone 
