J8.1 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 3 



The two remaining specimens, which probably came from Lithoden- 

 ou in Arizona, are black throughout. The larger is about 8 feet in 

 Sgth and decidedly elliptical in cross-sectiou, the larger end measur 

 o*20i inches in long and 13£ inches in short diameter, the smaller 

 ll7 inches in long and 12 inches in short diameter. Tbe smaller 

 .ecimen is G feet 4 inches long, and is also considerably compressed, 

 e long and short diameter of the large end being respectively 24 by 

 I inches and of the small end 17 by 12 inches. 



In regard to the geological horizon to which these fossils belong, 

 a j. J. W. Powell, who has recently visited this section of the country, 

 clines to regard them as of Jurassic age. Other evidence points to 

 ie ir Cretaceous age, but until further and more definite knowledge 

 obtained these views must be regarded as uncertain. 

 A microscopical examination shows the internal structure of all to 

 we been tolerably well preserved, the cells having suffered but little 

 om the pressure to which the trunks had been subjected. Tbey all 

 Rig to the genus Araucarioxylon, and probably are of the same 

 fees. The two from Lithodeudron are absolutely identical in struct- 

 te, but the one from Fort Wingate, as it lacks some of the essential 

 aaracters, is referred provisionally to the same species. More abun- 

 ant material may clear up all doubtful points. 



Tbe only material that has been examined microscopically from this 

 art of the country, so far as I am able to learn, was that collected by 

 >r. Baldwin Mollhausen, a German traveler, in the valley of Rio Seco, 

 [e W Mexico, about the year 1854. These specimens were submitted to 

 >r. H. R. Goppert, of Berlin, who reported upon them in Mollhausen's 

 Reise vom Mississippi nach den Kiisten der Siidsee," p. 492. Among 

 liese specimens Goppert detected a new species, which, in honor of the 

 iscoverer, be named Araucarites MoWiausianus, but did not indicate 

 ■ay of tbe characters upon which it was founded, nor can I find that 

 t was ever subsequently described. The specimens belonging to tbe 

 National Museum represent an uudescribed species of Araucarioxylon 

 Araucarites Presl.), which may possibly be the Araucarites Mollhausi- 

 inus of Goppert, but it is manifestly impossible to decide this, except 

 >y an examination of the original specimen which Goppert says (I. c.) 

 s deposited in the mineralogical cabinet of the University of Berlin. 

 : have consequently decided to describe these species as new under the 

 bllowing name : 



Araucarioxylon arizonicum, n. sp. 



Araucarites mollhausianus t Gopp., in Mollhauseu's " Reise," p. 492. 

 Diagnosis.— Annual ring not apparent to the naked eye, but under 

 ;be microscope observed to be present, tbe yearly growths being sepa- 

 rated by a layer of 2-5 tangentially compressed cells ; tracbe'ids with 

 noderately thick walls, which are provided on the radial sides with a 

 single row of large contiguous pores or rarely with two rows of alter- 

 nating pores, and on tbe tangential sides with numerous, separated, 



