MAZATLAN BIVALVES 155 



Hob. Bay of Panama, in a few fathoms of water, Cuming ; 



C. JB. Adams. La Paz ; Lieut. Green. Mazatlan ; not 



uncommon ; L'pool fy Havre Coll. 



Tablet 692 contains a young specimen perhaps belonging 

 to this species, but differing from the rest in having the liga- 

 mental groove closed, and the scaly processes larger and more 

 spathulate : long. 2 '3. 



Tablet 693 contains a very young, [highly coloured valve, 

 '22 across. 



Tablet 694 contains a young sp. from Pinna, with Ostrese, 

 Vermetidse, &c. attached : long. 4*. 



Tablet 695 contains a finely grown adult sp., with Verme- 

 tidse, Chama &c. attached. 



Tablet 696 contains a sp. presented by F. Bacon, Esq., 

 displaying the interior. The outside contains burrows of 

 Parapholas calva, Gastrochsena ovata and truncata, Lithopha- 

 gus aristatus and plumula, &c. Two Pholads remain in situ, 

 having forced themselves against the interior of the shell. 



Tablet 697 contains a fragment of an attached valve, 2 * 5 in. 

 thick, with numerous burrows, displaying the white marble- 

 like interior portion, and the coloured exterior bored by 

 worms. 698, 2 fragments displaying the colour layers. 699, a 

 fragment exhibiting the orange red colour. 



209. ? SPONDYLUS , sp. ind. 



Tablet 700 contains a fragment with very large flattened 

 tubercular knobs.' 

 Ha b. Mazatlan ; in Chama washings ; L'pool Col. 



GENUS PLICATULA, Lam. 



210. PLICATULA PENICILLATA, n. s. 



P. t. alba, brunneo scepe tenue penicillatd, elongatd, liaud 

 valde costatd, margine plerumque plicatd ; dentibus cardinali- 

 ties elongatis, rugosis, externis magnis valde extantibus ; internis 

 angustis, lig amentum minimum tubulatum amplectentibus ; cica- 

 trice musculari subcirculari seu subovali. 



Plicatula dubia, var., Sow. ms. in Mus. Cuming. 



A small specimen in Mr. Cuming's collection did not present 

 sufficiently marked characters, in the judgment of Mr. Sowerby, 



