BRITISH OYSTERS ! OLD AND NEW. 
217 
they cannot lie flat, but grow vertically upwards side by side. 
Hidalgo gives its habitat as Corunna and the Tagus, with a littoral 
habitat. Attempts to naturalise it in British waters have not 
been very successful or productive. 
These may all be referred to the section Crassisostrea, Sacco, 
a group which discharge their eggs into the sea water, unlike our 
British shells, which retain the fry in their gills. (Dr. Dali, in 
litt.) 
OSTREA LUSITANICA, A. Bell. 
Under this name I figured (Rept. Yorks. Phil. Soc., 1892, p. 
73, pi. i., fig. i), a shell I found occasionally in the early Pleistocene 
mud deposit at Selsey in Sussex, where it occurred with 215 other 
species of molluscs, all of Lusitanian types. The shell is long 
and narrow in proportion, ranging up to 100 mm. by 45 mm. 
On p. 197 reference is made to a small elongated shell ascribed 
by Jeffreys to 0 . deformis Lamarck, which I showed did not agree 
with the author’s description in any way. Reeve’s figure 
(op. cit., plate v., fig. 8, d.), closely resembles this shell and both 
may be assigned to the present species. 
OSTREA VERTEX, sp. nov. 
Sir Gardner Wilkinson (Zoologist, 1865, vol. xxiii., p. 9559), 
describes finding at Tenby a small oyster with depressed end, 
only 2 inches long, by five-eighths of an inch in breadth, scarcely 
varying in width throughout its length. His description is that 
of a young shell having the “ half deck ” prolonged into a tail¬ 
like projection or spur, terminating in a sharp point corres¬ 
ponding with the hinge area and which in my own full grown 
example is much larger. This shell may be described as long, 
narrow, thin ; upper valve slightly convex, lower flatly convex 
to hollow or channelled longways ; beak and ligamental pit long, 
narrow, and usually produced as a spur. Scar purplish, hinge 
granulations indistinct. Length 70 mm., spur 15 mm., breadth 
45 mm. Colour cream yellow, thin outer skin, margin plain, 
surfaces smooth. One of the largest dealers in S. Wales tells 
me that this form is only met with at times, and one of his men 
to whom he showed my sketch at once recognized it as a local shell, 
not often met with. The name vertex refers to the projecting 
spur. (Plate xviii., fig. 25.) 
