930 DR. GWYN JEFFREYS ON THE MOLLTJSCA OF THE [NoV. 29, 



ralline and Red Crag, S. France and Italy. Post-tertiary : Hopton 

 in Suffolk and Calabria. 



1/ 1. Lyonsia. NORVEGicA, Chemnitz. 



Mya norvegica, Chemn. Concli.-Cab. x. p. 345, t. 170. f. 1647, 

 1648. 



L. norve(/ica, B. C. iii. p. 29, pi. ii. f . 1 ; v. p. 190, pi. xlviii. f. 2. 



'Porcupine' Exp. 1869: St. 1, 10, 14, 18, 23«, 35, 68. 1870: 

 Med. G. Bona, Benzert Road, Rasel Amoush. 



Distribution. Loffoden I. to the J5geau and Adriatic, and (accord- 

 ing to Dr. Philip Carpenter), Seniavine Straits in the North Pacific ; 

 2-162 fms. 



Fossil. Pliocene : Sicily. 



Not L. norvegica of Middendorff, which is L. arenosa, but pro- 

 bably Mya membranacea of Gmelin from Miiller's ' Prodromus,' and 

 Osteodesma inflatum of Danilo and Sandri. For other synonyms see 

 'British Conchology,' iii. pp. 31, 32. 



2. Lyonsia Formosa', Jeffreys. (Plate LXX. fig. 1.) 



Shell oval, equivalve, pearl}', thin, and semitransparent : sculp- 

 ture, numerous and close-set rows of minute tubercles, arranged 

 lengthwise ; the posterior side is also marked with from six to eight 

 diagonal flexuous ribs or folds, of which the innermost is the strong- 

 est and forms a keel ; there are, besides, traces of other flexuous ribs 

 in the middle and on the anterior side ; the posterior side has like- 

 wise a few rows of short but irregular prickles as well as the tuber- 

 cles : colour silvery-white : epidermis filmy and only perceptible on 

 the edges of the shell : margi^is rounded on the anterior side, gently 

 curved in front, with a slight sinuosity and contraction towards the 

 posterior side, which is somewhat truncated ; dorsal margin incurved 

 on each side of the umbo : beaks triangular, inclined to the anterior 

 side : ossicle pearlj', heart-shaped or notched at the posterior end : 

 cartilaye brownish-yellow, enclosing the ossicle ; pit oval, with 

 thickened edges : hinge-plate long and thick : inside highly polished 

 and iridescent: muscidar scars broad and distinct. L. 0'4, B. 0"65. 



'Porcupine' Exp. 1869 : St. 23. 1870: Atl. 3a; Med. .55, 



Distribution. 'Challenger' Exp. off Gomera, Canaries, 620 fms.; 

 off Carysfort in the Gulf of Mexico (Pourtales), 349 fms. ; Bay of 

 Biscay (' Travailleur ' Exp.), 552-600 fms. 



A most lovely shell, and one of tlie prizes of the deep-sea dredger, 

 who might be classed in the former part of Wordsworth's category as 



"Tliey who rather dive than soar." 



3. Lyonsia argentea", Jeffreys. (Plate LXX. fig. 2.) 



Shell triangularly oval, rather solid, opaque, and of a dull hue : 

 scidpture, a few slight ribs longitudinally radiating from the beak in 

 the right valve, none in the other valve, which, however, is strength- 



^ Beautiful. = Silvery. 



i 



