MAZATLAN BIVALVES 83 
116. Goutpra Pactrica, C. B. Ad. 
©. B. Ad. Pan. Shells, p. 275, no. 450, 
The only pair found (and that imperfect) was unfortunately 
smashed just after it had been sketched. 1t was of a rich lus- 
trous brown like Petricola robusta. The shell has all shades 
toadingy white. About 18 odd valves were found, by no 
means constant in their characters. The general appearance 
is remarkably like a little fossil Astarte noticed in a communi- 
cation made to the British Association, L’pool, 1854, (v. Re- 
port, p. 78,) flat, triangular (in that respect alone like Tellina 
Burneti) and with very distant ribs outside. These ribs are 
generally sharp, but sometimes rather flat and rounded. The 
anterior dorsal margin is concave in young specimens. The 
surface of the shell appears under the glass, covered with fine 
radiating stris; but under the microscope these lines are 
found to be simply the divisions between rows of parallel 
‘oblong dots, which most resemble the strung figs of commerce, 
and are laid in rows, side by side, over the surface of the shell. 
These show. through in very young specimens, and present a 
most beautiful appearance. Inside, one valve has a long 
anterior lateral tooth, a short distant posterior one, and 3 nar- 
row divergent cardinal teeth, of which the middle one lies 
between two broad pits, and the anterior joins on to the lateral. 
The other valve displays along posterior, and small distant | 
anterior lateral ; with 3 cardinals, of which one is the beginning 
of the posterior lateral, the middle rises between two pits, and 
the anterior is marginal, nearly obsolete. Muscular and pallial 
marks distant from margin. The largest valve measures 
long. °16, lat. °18, alé. °05. 
Hab.—Panama; not common; C. B. Adams.—Mazatlan ; off 
Chame and Spondylus, very rare ; L’pool Col. 
Tablet 414 contains 4 valves, of different ages, and a fresh 
fragment to shew the ‘strung-fig’ structure. 
117. GouLDIA VARIANS, 2. s. 
G. t. minima, subtrigond, subequilaterali, formd plus minusve 
angulato-rotundata, plus minusve elongata ; albidd, plus minusve 
fusco maculaté ; sublevi, striis incrementi, sive costis concen- 
tricis paucis seu nwnerosis ; superficie lineis granulosis radi- 
antibus creberrimis celaté ; umbonibus subspiralibus, haud 
conspicuis ; margine sumplici, appresso; dentibus lateralibus 
