ON MOLLUSCA OF THE WEST COAST OF NORTH AMERICA. 591 



VI. 54. 49. tGratelupia mactropsis, Conr., n.s. [? = Donax punctatostriatus.'} 

 ? Miocene. Isthmus of Darien. Resembles G. Hydeana, Conr. 

 Eocene. 

 w 55. 50. Meretrix Dariena, Conr., n.s. [Comp. Cyclina subquadrata.'} 



PMiocene. Isthmus of Darien. 



53. 51. Tellina Dariena, Conr., n.s. PMiocene. Isthmus of Darien. 

 VII 57. 52. Natica Ocoyana, Conr., rr.s. [Marked 51 on plate : err.] Oeoya 



or Pose Creek. 

 67. 53. Natica geniculata, Conr., n.s. Ocoya Creek. Resembles N. 



alveata. 



62. 54. Bullajugnlaris, Conr., n.s. Ocoya Creek. 

 69. 55. Pleurotoma transmontana, Conr., n.s. [Marked 60 on plate : err. 



Closely resembles Chrysodomus dims, Rye.] Ocoya Creek. 

 56. Pleurotoma Ocoyana, Conr., n.s. [Omitted in the text.] Ocoya Cr. 

 72. 57. Syctopus [Ficula.] Ocoyanus, Conr., n.s. Ocoya Creek. 

 VIII. 73. 58. Turritetta Ocoyana, Conr., n.s. Ocoya Creek. 

 76. 5. Coins arctatus, Conr., n.s. Ocoya Creek. 

 75. 60. Tellina Ocoyana, Conr., n.s. Ocoya Creek. 



77. 61. Pecten Nevadanus, Conr., n.s. Very like N. Humphreysii, Mary- 

 land, Miocene. Ocoya Creek. 



TX. S3. 62. Pecten calilliformis, Conr., n.s. Very like P. Madisonius } Say, 

 Virginia, Miocene. Ocoya Creek. 



The following species are not described in the text, but quoted in the list. 

 Vide p. 320 : 



VIII. ?78. 63. Cardium, sp. ind. Ocoya Creek. 



64. Area, sp, ind. Ocoya Creek. 



,. ?80. 65. Solen, sp. ind. Ocoya Creek. 



,. rc^l. 66. Dosinia, sp. ind. Ocoya Creek. 



,', ?79. 67. Venus, sp. ind. Ocoya Creek. 



68. Cytherea ?decisa, Conr. Ocoya Creek. 



69. Ostrea, sp. ind. San Fernando. 



70. Pecten, sp. ind. San Fernando. 



71. Turritetta biseriata, Cour., ?n.s. San Fernando. 

 VII. ?58. 72. Trochus, sp. ind. Benicia. 



P59. 73. Turritella, sp. ind. Benicia. 



?71. 74. Buccinum ? inter striatum. San Pedro 



* 75. Anodonta Calif orniensis, 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 species being 

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

 addition to the species tabulated in this Report, he quotes, as having been 

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

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

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

 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 Miocene. 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 later 



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

 toxt. It is unsafe to conjecture the genus to which many of them belong, but it is pre- 

 nuraed that they relate to the indeterminate species here quoted. 



77 



