MAZATLAN BIVALVES 165 



Hab. — Bay of Panama, in a few fathoms of water, Ctiming ; 



C. B. Adams. — L-d Paz ; Lieut. Green. — Mazatlan ; not 



unconomon ; L'jiool ^* Havre Coll. 



Tablet 692 contains a young specimen perhaps belonging 

 to this species, but diftering from the rest in having the Uga- 

 mental groove closed, and the scaly processes larger and more 

 spathulate : long. 2 '3. 



Tablet 693 contains a xevy young, ^highly coloured valve, 

 "22 across. 



Tablet 694 contains a young sp. from Pinna, with Ostre*, 

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



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

 tida.', Chama &c. attached. 



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

 displaying the interior. The outside contains burrows of 

 Parapholas calva, Gastrochana ovata and truncata, Lithopha- 

 gus aristatus and plumida, &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 coloui-ed exterior bored .by 

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

 fragment exhibiting the orange red colour. 



209. ? Spondylits , sp. hid. 



Tablet 700 contains a fragment with very large flattened 

 tubercular knobs. 



Sah. — Mazatlan ; in Chama washings ; L'pool Col. 



GfiNTJs PLICATULA, Lam. 



210. Plicatula penicillata, n. s. 



P. t. alhd, hrunneo scepe tenue penieillatd, elongatd, hand 

 valde eostatd, margine plerumque plicatd; dentibus cardinali- 

 bus elongatis, rugosls, externis magnis valde extantibus ; internis 

 angiistis, Ugunientmn minivium tubidatum amplectentibus ; cica- 

 trice musculari subcireulari seu siibovali. 



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



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

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



