%i)Y''] PROCEEDINGS OF THE NATIONAL MUSEUM. 373 



<4('iiu.s that the (k'teiiniiiatioii must bo luuic or h'ss aibitiaiy. The 

 ^l//M<ro«.ysi)ecimeus do not differ essentially from the Panama and Gulf 

 of California form, which both ('. !>. Adams aii<l Philip Carpenter de- 

 termined as Orbigny's species. It is i)robably tlie same as flexnosa 

 iSby., as stated by Carpenter, to whose comments in the "Mazatlan 

 catalogue " reference is suggested. 



Family MYTILIDyE. 



Genus MYTILtJS Linn6. 

 6. Mytilus luultifortnis Cpr. 



Valves, beach (Mus. J^o. 102353). 



Hood Island. 



This species was described by Carpenter from Mazatlan shells, and 

 the Galapagos valves are appaiently identical. Dr. .Jones dete<;ted 

 perfect examples and odd valves of M. cunei/ormis { = j\f. angiistanus 

 Eve.) at Chatham Island. 



(ienuH SEPTIFER Kcdiiz. 

 7. Septifer Cumingiaiius I>kr. 



One valve, beach (Mus. No. 102352). 

 Hood Island, 



Cuming collected this species at Panama and Carpenter includes it 

 in his Mazatlau list. 



(ieuus MODIOLA J^aiiiank. 

 8. Modiola capax ? Cpr. 



One example, very small, beach. 

 Hood Island. 



Probably, but not certainly, the above species, which is credited to 

 the Galapagos in the Cuming collection now in the British Museum. 



Family ARC ID^]. 



(ieiiu.s ARCA Laiiiid'cU. 



Subyiiiui.s BYSSOARCA SwaiiiMDii. 



9. Area (Byssoarca) solida Sliy. 



Valves, beach (Mus. Mo. 122131). 

 Indefatigable Island. 



10. Area (Byssoarea) gradata \Uuil. Ar Sl>y. 



Valves on beach. 



James, Hood, Indefatigable, and Chatham islands. 



Three perfect valves from rlames Island, one in good condition from 

 Chatham, and one broken valve from Indefatigable; also one from 

 Hood Island. 



