80 DESCRIPTIVE CATALOGUE 



Thompson (1912) is that the ancestors of Abies normally showed 

 that feature in their wood. 



Until the various parts of the plants are more fully known 

 and are definitely correlated, it is impossible to ascertain to 

 what extent the ancient forms differed from those now living. 

 That the fundamental differences may have been considerable 

 is indicated by the existence of the interesting Prcjnnus (see 

 Hollick & Jeffrey, 1909, and Slopes & Kcrshaw, 1910). 



Genus PROTOPICEOXYLON, Gothan. 

 [Foss. Holz. Konig-Karls-Land, 1907, p. ;$LV| 



Diagnosis. A woody Gymnosperm of normal abk'tinoan 

 structure, save that resin-canals are present only in a vertical 

 direction. Normally the medullary rays are entirely uniseriatr. 

 and show typical abietinean pitting. The epithelium of the 

 resin-canal is thick-walled and pitted ; the canals may he either 

 large or small, but are developed normally. There may be 

 additional traumatic canals, which run in multiseriato rays, 

 abnormally developed. 



Gothan's original account of the genus is based on the single 

 new species P. extinctum, and he gives no separate generic and 

 specific diagnosis, but describes it as c/enus tt species novum as 

 follows : " Abictineenholz, normalerweise nur mit vcrtikalen 

 Harzgiingen. Diese im allgemeinen nicht sehr zahlreich (bci 

 Wundreiz aber sehr /ahlreich, oft in y.usammenhiingenden Serien 

 auftretend) ; bei "Wundreiz auch hier und da horizontale, in 

 Markstrahlen verlaufende Harzgange von ungewohnlicher 

 Grosse, sich hier (lurch schon als Anomalien verratcnd ; sonst 

 durchaus ohne horizontale Harzgange. Markstrahlen cinreihig, 

 Markstrahltiipfel klein, rundlich (sicher behoft gewesen); ca. 

 2-4 pro Kreuzungsfeld. Holzparenchym fehlend ; die letzten 

 Holzzellen des Jahresringes mit deutlichen kleinen Tangential- 

 tiipfeln." 



In a later account of the species Gothan (1910) somewhat, 

 re-arranges this diagnosis, and includes in his new species the 

 already-described form Pin ties cavernosus, Cramer, or Cedro- 

 xylon cavei'iiosum. 8chcnk. Ho does not diagnose the genus 

 separately. 



