.UKASSIC FLORA OF DOUCiLAS COINTY. ORK(i. 141 



54. Williainsoniu ^ sp. Fuiit. Bracts of tJG. ('\ rlopiivs (irctriniciisis Font . 



Williainxniia Xcis. 2. a, I), f. 67. Splii'iKilcjjidiuni oi-ciidiicnsi' 1 

 5"). (iiiik^u (lijiitata (Bron^ii.) IIoci-. sj). 



56. Gink^i) lluttoiii (Stcnih.) llccr. 6S. Saman)|)sis '. (irci^oiicnsis I- 



57. Gink;i;() Iluttoni inagiiilolia Font. u. sp. 



var. 61). Malr anient of conifer. 



55. (iiiiki^o le])i(la ITeer. * 70. Yuccilcs heltan^eiisi.s Sa]). ? 

 5i). Ciinki;o .sibiiica Ileer. | 71. I'lideternuiicd leaf. No. 1. 



60. tiiiikiio s]). Font. Afjenant Ciink- 72. I'lideterniiucd leaf, No. 2. 



iTiis. I 7o. Carj)olitlius olalleiisis Ward ii. s]). 



61. I'lui'iiicopsis ? sp. Font. 1 74. Carpolitluis Bucklandii WilJn.^ 



62. Taxites zaniioides (Leek.) Sow. 75. ('ar]iolitluis oregoneiisis F(jiit . n. sp. 

 6;;!. Bracli\])liyllnni iiianiillare Brongn. | 76. ('ar])olitlius elongatus Font. n. sj). 



64. Araucarites ? sp. Font, (cone scale). 77. Carpolitluis dougla.sensis Font. n. sp. 



65. Finns Nordenskioldi Heer. 



Ill determiniiiji ffoni these plants the age of the strata that contahi 

 them, 40 must be eliminated as of no value. There are 22 new species, 

 2 new varieties, 7 species not positively determined, and 9 forms tiot 

 specifically determined. It may be said of these that none are incom- 

 patil)le with the conclusion that the age of the strata is Jurassic. On 

 the contrary, so far as they throw any light on the question of age, they 

 indicate that it is Jurassic. The species that were doubtfully determined 

 are the only ones that have any bearing on the question. They have at 

 least some affinity with forms known from established geological horizons. 



The plant doubtfully determined as Adiantites Nymj)liarum has an 

 affinity- with Heer's species from the Lower Oolite of Siberia ; Ptero))liylIum 

 minus comes from the Lower Oolite of Yorkshire; Ctenis (lunculata is 

 found only in the Oroville strata, which are proljably Lower Oolite in age; 

 Marchantites erectus comes from the Lower Oolite of Yorkshire; Yuccites 

 hettangensis is obtained from the Infralias of Hettange, a lower horizon 

 than the Lower Oolite; Carpolithus Bucklandii comes from the Lower 

 Oolite of Yorkshire. Thirty-seven species and varieties, over half of the 

 entire number, are forms found in formations whose age is more or less 

 fully established. 



The following species have been found only in the Oroville strata of 

 California: Cladophlebis vaccensis, Tamiopteris orovillensis, Macrotamiop- 

 teris californica, Cteno])hyUum angustifolium, Ctenophyllum Wardii, Cleiiis 

 orovillensis, Ctenis grandifolia. There ai'e thus 7 species found only in 

 the Oregon and Oroville l>eds. 



