682 



NEW YORK STATE MUSEUM 



Didymograptus ellesi sp. nov. 



Plate 14, figures 22-24 



Didymograptus (Leptograptus) sp. nov. {pars) Ruedemann. N. Y. State 

 Paleontol. An. Rep't. 1902. p.589. 



Description. Primary disk and nema not observed. Sicula relatively 

 long, attaining a length of 1.2 mm, slender, very conspicuous [fig.23] on 



account of the slender character 

 of the rhabdosome. Point of 

 gemmation of first and second 

 thecae not observed, that of 

 the first theca apparently in the 

 apical half of the sicula. Branches originating near the aperture of the sicula 

 at different levels of the same, but slightly curved, of somewhat rigid appear- 

 ance, slightly declined (angle of divergence quite uniformly 170°), very thin, 

 very gradually widening from a proximal width not quite .2 mm to one of .4 

 mm ; attaining a length of 14 mm or more. Thecae very slender, widening 

 but very little toward the aperture, numbering 10 to 12 in 10 mm ; three times 

 as long as wide, inclined at an angle of 8° to 10° ; overlapping about one eighth 



Pig. 75 Didymograptus ellesi sp. nov. 

 of one branch. Obverse view. Deep Mil. x7 



Sicula and part 



Kg. 76 Didymograptus ellesi sp. nov. Enlargement of a branch 

 of the specimen reproduced on pi. 14, fig. 2Z. Deep kiU. x6 



of their length, the outer or apertural margins straight, the latter perpendicular 

 on th(} axis of the theca. 



Position and locality. Found on a single surface at the base of bed 3 at 

 the Deep liill, associated with D. nanus and D, gracilis. 



Hemarlcs. This form is readily distinguished from the associated, simi- 

 larly delicate D. gracilis by the more rigid expression and uniform, slightly 

 declined direction of the branches. Its nearest relations are clearly with D . 

 a f f i n i s Nicholson among the types of Didymograptus and with B r y o - 

 graptus lapworthi, here described, among the older multiramous forms 



