ON MOLLUSCA OF THE WEST COAST OF NORTH AMERICA. 591 



P.»t«« Fig. No. 



VI. 64. 41). fGrnti'lupia mactrn/m's, Cnnr., n.s. [? = D(>nax ptmctatnxtn'atun.l 



i'Mioceue. Isthmus of Darien. Itesembles G. JJydeana,CoixT. 



P^ocene. 

 u 55. 50. Mcretru: Darienn, Conr., n.s. [Comp. CycUna subquadrata.'\ 



I' .Miocene. Isihimis of Darien. 

 Tellina Dnru'na, Conr., n.s. PMiocene. Isthmus of Darien. 

 Natica Ori>i/nna, Conr., n.s. [Marked 51 on plate : err.] Ocora 



or I'ose Cri't'k. 

 Natica (/enivulafa, Conr., n.s. Ocoya Creek. Resembles iV. 



aireata. 

 Jinlldjuffularis, Conr., n.s. Ocoya Creek. 

 rUurototna tran^moiitana, Conr., n.s. [Marked 60 on plate : err. 



Closely resembles Chrysodumus dims, Kve.J Ocoya Creek. 

 rL'urotoma Ocoyana, Conr., n.s. [Omitted in the text.] Oco^a Cr. 

 Syrtopus [Ficula ] Ocoynnm, Conr., n.s. Ocoya Creek. 

 Turritella Ocoyana, Conr., n.s. Ocoya Creek. 

 i'ohts arctatits, Conr., n.s. Ocoya Creek. 

 Tilliiia Ocoyana, Conr., n.s. Ocoya Creek. 

 Pecteti Xeradanwi, Cour., n.s. Very like iV. IIumphrey4iy 5lA»y- 



land, Miocene. Ocoya Creek. 

 TX. S3. 62. Pecteii caldliforniis, Conr., n.s. Very like P. Madisonius, Say, 



\'irgiuia, Miocene. Ocoya Creek. 



The follo\nng species are not described in the text, but quoted in the list. 

 ride p. '&20 :— 



Cardiiim, sp. ind. Ocoya Creek. 



Area, sp. ind. Ocoya Creek. 



t>olen, .sp. ind. Ocoya Creek. 



Dosinia, sp. ind. Ocoya Creek. 



Venu<, sp. ind. Ocoya Creek. 



Cythiyea rdccisa, Conr. Ocoya Creelc 



Ostrea, sp. ind. San f^emando. 



Pectcit, sp. ind. San Fernando. 



Turritdla biseriata, Conr., Pn.s. San Fernando. 



Trochus, sp. ind. Benicia. 



Tiirn'h'/la, sp. ind. Benicia. 



liuccinum ^interxtn'atum. San PedrO: 



Aiiodonta Calif ornie)ms, Lea. Colorado Desert. 



Mr. Conrad, than whom there is no higher authority for American Tertiary 

 fossils, considers the age of the Eocene boulder ascertained ; and that " the 

 deposits of Santa Barbara and San Pedro represent a recent formation, in 

 which {teste Blake) the remains of the Mammoth occur: and the shells indi- 

 cate little, if any, change of temperature since their deposition." But he 

 acknowledges that the intermediate beds are of uncertain age. Those on 

 Carrizo Creek he refers to the Miocene, some characteristic sjMJcies being 

 either identical with the Eastern Miocene or of closely relpted forms. In 

 addition to the species tabulated in this Report, he quotes, as ha^^ng been 

 collected in California by Dr. Heermann, " Mereenaria perlaminosa, Conr., 

 scarcely differing from M. DucateUi, Conr. ; and a Cemoria, Pandora, and 

 Cardita of extinct species, closely analogous to Miocene forms." The casta 

 from Ocoya Creek were too friable to be preserved, and are figured and de- 

 scribed from Mr. Blake's drawings ; these also are regarded as Mio(:;ene. The 

 San Diegan specimens are too imperfect for identification ; they are referred 

 to the Miocene by Conrad, but may perhaps be found to belong to a lat«r 



• Several fossils are figured in plates vii. and viii., to which no reference is made in the 

 text. It is unsafe to conjecture the genus to which many of them belong, but it i» pro- 

 turned that they relate to the indeterminate species here quoted. 



77 



