ACEPHALA. 461 
Length seven-tenths of an inch; height nine-twentieths of an inch ; 
breadth one-fourth of an inch. 
Found in latitude 47° 30’ S., long. 59° 50’ W., adhering to the 
giant fucus seen floating in these regions, and abounds on kelp in 
Orange Harbour, where some were found an inch and a half in 
length. 
This seems clearly to be the shell described by Lamarck without a 
locality, and figured by Delessert; but as it is a curious shell, and no 
full description of it is to be found, it is given here. It would seem to 
be the same species alluded to in the ‘* Voyage of the Astrolabe,” (Zool. 
ili. 216), as “a Modiola rare and perhaps new, which attaches itself to 
the fucus, a short distance at sea,” near the Falkland Islands. 
OsTREA GLOMERATA (Gould). 
T. crescentica, lata, sinistrorsum arcuata, solidiuscula, planulata, sca- 
briuscula, laminis dentatis prope marginem foliata, nigricans et albo- 
radiata ; margine undulato: interior alba ; fovea apical profunda ; 
cicatrice nigricante ; marginibus aut simplicibus aut lineolatis et prope 
cardinem granulatis ; limbo cortical purpureo et viridi varvegato. 
Ostrea glomerata, GouLp; Proceed. Boston Soc. Nat. Hist., 1. 346. 
Dec. 1850. Expedition Shells, 96. 
SHELL orbicular crescentic, turning to the left, right side convex, 
left concave, of moderate size and thickness, and shallow cavity. 
Margin of shell undulated cr plicate, the outer shell-substance extend- 
ing, in a variegated green and slate-coloured margin, beyond the inner 
nacreous portion; edge simple, or minutely lineated in a radiate manner ; 
the upper valve is furnished with a few irregularly disposed granules 
near the hinge. on each side, with corresponding pits in the lower 
valve; hinge area broad, furrowed. Colour of interior white, with a 
slaty tint to muscular cicatrix, and some olive maculations on the 
margin of upper valve. Exterior of upper valve tolerably smooth, with 
dentiform foliations near the margin, like Meleagrina. Colour slaty 
black, with a few, well-defined white radiations. 
116 
