320 C. J. Hylander — Mid-Devonian Callixylon. 



Specific Characters. 



Comparison of the type sections of Callixylon Oweni 

 with those of the present Eighteen Mile Creek wood 

 sections, reveals specific variation. There are the same 

 discontinuous pit groups and obscure growth rings, but 

 the tracheids are of a consistently smaller size not 

 accounted for by compression or accidental variations, 

 and the wood rays are relatively broader. Therefore, 

 there need be no doubt in naming it after its finder of 

 sixty years ago, who later became so famous as an 

 indefatigable collector and paleontologist. 



Callixylon Marshii sp. no v. Tracheids 35-45/* in 

 diameter, walls 3-5/* thick, radial pits of the bordered 

 crossed slit type, arranged in from one to three vertical 

 rows in discontinuous groups of few to 12 or 13 pits to 

 the grouping, groupings radially aligned ; wood rays few 

 to 20 cells deep, two cells wide, conspicuously broad in 

 cross section; growth ring of primitive type present but 

 difficult to see. Horizon, upper mid-Devonian of New 

 York. Type locality, Eighteen Mile Creek, New York. 



The following comparison is added for convenience : 

 Trans. Sect. — Diameter of tracheids : C. Marshii, 35-40/* ; 

 C. Newberryi, 44-55/*; C. Oweni, 45-60/*. Thickness of 

 walls : C. Marshii, 3-5/* ; C. Newberryi, 6/* ; C. Oweni, 

 5/*. Growth rings absent in C. Newberryi, also C. Tri- 

 filievi, present in the other two species. Radial long. 

 Sect. Pit groups : 3-13 in C. Marshii, 6-13 in C. New- 

 berryi, and 3-40 in C. Oweni. Pit diameter: 9.3/* in C. 

 Newberryi, 8-10/* in C. Marshii, and 10-11/* in C. Oweni. 

 Tang. Sect. Height of rays : C. Marshii, 1-20 ; C. New- 

 berryi, medium height; C. Oweni, 1-40. Thickness of 

 rays : C. Marshii, at least 2-seriate ; C. Newberryi, 

 3-seriate rarely; C. Oweni, 2-seriate. 



Thus it is seen that the C. Marshii is closer to C. New- 

 berryi (2) than to C. Oweni. And this is an interesting 

 point since the C. Newberryi is given from the mid- 

 Devonian of Ohio. Neither of these forms can be con- 

 fused with the forms called Badoxylon Ouangondianum 

 and D. Halli (2), from the mid-Devonian of New York. 

 These are distinct as forms with four and five pit rows, 

 the adpressed pits, and broad wood rays. They are men- 

 tioned merely because figured by Dawson along with the 



