MAZATLAN BIVALVES $3 



116. GouLDiA PACIFICA, C. S. Ad. 



C. S. Ad. Pan. Shells, p. 275, no. 450. 



The only pair found (and that imperfect) was unfortunately 

 smashed just after it had been sketched, It was of a rich lus- 

 trous brown like Petricola robusta. The shell has all shades 

 to a dingy 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 striae ; 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, an<^ 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 a long 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. 'IS, alt. *05. 

 Hob. Panama ; not common ; C. IB. Adams. Mazatlan ; off 



Chamse 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. 



j 117. GOULDIA VAEIANS, n. s. 



G. t. minima, subtrigoqd, subcequilaterali, forma plus minusve 

 angulato-rotundatd, plus minusve elongatd; albidd, plus minusve 

 fusco maculatd; subleevi, striis incrementi, sive costis concen~ 

 tricis paucis seu numerosis ; superficie lineis granulosis radi- 

 antibus creberrimis ccelatd ; umbonibus subspiralibu-s, haud 

 conspicuis ; margine simplici, appresso ; dentibus lateralibus 



