28 PANDORID/E. 



and afterwards P. 7'ostrata ; the young is tlie P. flexuosa 

 of Philippic and the animal the Hyjwgcea gibba of Poli. 

 It is also the Trutina solenoides of Brown. The variety 

 obtusa Avas described by Meuschen as Anomia tabacca, 

 by Montagu as Solen pinna, and by Leach as P. glaci- 

 alis ; the young is the P. oblong a of Philippi. Lamarck 

 changed the specific name imposed by Linne^ either 

 from caprice (as seems to have been his custom), or on 

 the ground that it denoted an essential character of the 

 genus and therefore Avas superfluous. I am not satisfied 

 with this reason, believing that all designations, Avhether 

 generic or specific, are merely symbols of distinction, 

 and that the law of priority in zoological nomenclature 

 oui!:ht not to be disrcGrarded because the name of one 

 species represents a character that is common to others 

 of the same genus. I have restored the original name, 

 by which this species is w^ell known throughout the 

 greater part of Europe. 



Genus II. LYON'SIA*, Turton. PL II. f. 1. 



Body oblong, somewhat compressed, rather thick : ffills 

 forming apparently a single leaf on either side, in consequence 

 of each pair being doubled upon itself: palpn long and narrow : 

 foot tongue-shaped, rather large, flattened, and provided with 

 a byssal groove. 



Shell oblong, nearly equilateral, finely striated lengthwise ; 

 right valve more convex than the left : epidermis fibrous : 

 himje furnished w^th a free plate or ossicle, which covers the 

 cartilage : muscular scars slight ; anterior oblong, posterior 

 roundish. 



A link connecting the Pandoridae with the Anatinida, 

 having the same shape and pearly nature as the former, 

 and the peculiar hinge-process or ossicle of the latter 



* Named after the late Mr. W. Lyons, an active British concliologist. 



