March 29, 1895.] 



SCIENCE. 



339 



as well be stated here that although a large 

 and voluminous repoi-t containing 280 

 quarto pages and 39 plates, it still comes far 

 short of covering the material that is now 

 in the author's hands. The collections were 

 sent to him in instalments almost every year 

 and are still arri^'^ng, but it was necessary 

 to fix some limit to the publication, which 

 was closed at a certain date and the work 

 sent to press, since which time other col- 

 lections have been received, which were also 

 careiully examined on that occasion at the 

 Chateau of Fonscoloml)e, the country resi- 

 dence of the Marquis. Hi kilometei-s north 

 of Aix, and upon which he was at the time 

 actively eng-aged. These will be reported 

 upon in a subsequent memoir. The re- 

 markable parallelism between the plant 

 bearing dejwsits of the west coast of Portugal 

 and those of the eastern part of the United 

 States, and especially between the Lower 

 Cretaceous of Portugal and our Potomac 

 formation, gives an esj)ecial interest to this 

 memoir. 



TUE JCRASSIC FLORA. 



Ix America there is a decided time hiatus 

 between the lowest Potomac beds and the 

 next plant bearing horizon below, which is 

 now regai'ded as belonging to the extreme 

 Upper Triassic and as about the ecjuivalent 

 of the Keuper deposits of Lunz, in Austria.* 

 In Portugal, on the contrarj% there appear 

 to be no plant bearing horizons in the Trias 

 proper, but in the Jurassic, which is ab- 

 sent in this country, a considerable num- 

 ber of such deposits have been found. M. 

 Choftat, who prepared the geological part of 

 this memoir, follows as closely as possible 

 the nomenclature of the French geologists, 

 and it is found that plant beai-ing horizons 

 occur in the Infralias, part of which may 

 be as low as the Rhetic, and some of which 

 is referred to the Sinemurian ; in the Lias ; 

 in several of the properly Oolitic beds 



*See Bull. Gciil. Soc. Am., Vol. Ill, 1891, p. 31. 



(Toarcian, Bajocian, Callovian, etc.); in 

 several members of the Corallian ; in the 

 Kimmeridgian, and in the Portlandian. 

 The Jurassic deposits of Portugal consist of 

 sandstones and limestones, the former pre- 

 dominating below; and while all of them 

 may not be of marine oi-igin, so large a part 

 is fossiliferous that by the aid of the careful 

 stratigi-aphical investigations of the Portu- 

 guese geologist it is possible to fix the posi- 

 tion of the plant beds with relation to 

 those holding animal remains, a fact which 

 is of the utmost importance in deter- 

 mining the validity of the evidence of 

 fossil plants in such countries as Amer- 

 ica, where, for the most part, no such guide 

 exists. 



The Jurassic floi-a of Portugal, as em- 

 braced in the present memoir and in that 

 of Heer alreadj' mentioned, consists of 122 

 species, of which 22 are Infralias, 1 Lias, 8 

 Oolite, 8 Corallian and 88 Kimmeridgian. 

 It is subdivided into (3 Alg?e, 6 Equiseta, 

 70 ferns, 7 Cycads, 24 Conifers and 9 Mo- 

 nocotjiedons. Of the ferns, which so largely 

 predominate, 27 species belong to the genus 

 Sphenopteris, 8 to Cladophlebis, 8 to Scler- 

 opteris, and 4 each to Pecoptcris and HjTne- 

 nophj'llites. Of the conifers, which come 

 next in importance, 5 belong to Pagiophyl- 

 lum, 4 to Brachyphyllnm, and .3 to Thuyites. 

 The cycads belong to the two genera Podo- 

 zamites and Otozamites. Seven of the Mo- 

 nocotyledons consist of small blades and 

 culms of gi-asses, grouped under the genus 

 Poacites. 



A comparison of this Jurassic flora with 

 that of the American Trias reveals the fact 

 that while only 3 species, Cheirolepk Mi'in- 

 ■^teri, Pagiophyllum peregrinum and Palmya 

 Brown It, are common to the two, there are 

 14 genera that occur in both. In the num- 

 ber of species the two floras as now known 

 are almost equal, that of the American 

 Trias numbering 119, while that of the Por- 

 tuguese Jurassic numbers 122. It is there- 



