26 MAZATLAN BIVALVES 
Famity PANDORIDZ. 
Genus LYONSIA, Turton. 
Syn. Mytilimeria, Conr. Magdala, Leach. 
36. Lyonsra picta, Sow. 
Proc. Zool. Soc. 1834, p. 88.—? B. M. Cat. D’ Orb. Moll. p. 58, 
no. 506. 
?=L,. cuneata, D’Orb.—B. M. Cat. loc. cit. 
?= Anatina cuneata, Gray, Spic. Zool. vi. 1828. 
One perfect specimen of this remarkable shell was found by 
Master F. Archer, “burrowing” [? nestling] in Spondylus, and 
now graces his father’s collection. It gapes almost as much as 
Gastrochena, and displays a large ossicle within. The lunular 
portion is deeply excavated, and the posterior very greatly 
produced. Epidermis rugose, occasionally displaying fine radi- 
ating ridges. The growth is irregular, as usual in nestlers. The 
amount of gape varies considerably in Mr. Cuming’s specimens. 
Size of Mr. Archer’s specimen: long. ‘8, lat. 1°2, alt. * 64. 
The few fragments I found are known at once by the peculiar 
microscopic structure, described by Dr. W. B. Carpenter in 
Rep. Br. Assoc. 1847, p. 105. 
Hab.—Attached to particles of sand in 11 fm., Isl. Muerte, 
Cuming.—Vancouver’s Island, Col. Cuming—Mazatlan : 
nestling in Chame, &c., extremely rare: L’pool Col.—? Arica, 
(Peru,) D’ Orbigny.—The South Temperate analogue appears 
to be L. Patagonica, ‘‘Northern Patagonia, San Blas,” 
D Orb.—The W. Indian analogue is L. plicata, Gray. - 
Tablet 84 contains a perfect young specimen, just beginning 
its gape, and displaying the radiating strie ; also a fragment of 
an older one, shewing the hinge.—85, drawings of Mr. Archer’s 
specimen, made by Master John Jackson. 
Another species of Lyonsia, allied to A. cuneata, Gray, has 
been brought from Mazatlan: but as all the fragments even, in 
the L’pool Col., clearly belonged to L. picta, I have not ventured 
to include it. Like L. picta, it varies extremely in shape and 
gape: the latter being generally small, sometimes wanting. 
Texture smooth, extremely thin, white, glossy. 
