032 NEW YORK STATE MUSEUM 



D icliograp t n s ] ogani Roemer & Freeh. Lethaea palaeozoiea. 1897. 1:595, 



%.162 

 Loganograptus logani Elles. Quar. Jour. 1898. 54:4:76 

 Lo ga'n ogr a p t us logani Ruedemann. N. Y. State Paleontol. An. Rep't. 1902. 



p.556, 570 

 Loganograptus logani Elles & Wood. Monogr. Brit. Grapt. ptl. Pal. Soc. 



for 1902, p.81, pl.ll, fig.la-g 



Description. Sicula, nema and primary disk not observed. Rhabdo- 

 some consisting of relatively long (abont 2 . 1 mm) branches of tlie first 

 order (funicle), dividing dichotomousl}" into four short branches of the second 

 order (about 1.1 mm long). Twice repeated dicliotonious division in equally 

 short intervals leads normally to 16 branches of the fourth order. Sup- 

 pression of one or the other of the third dichotomies, or the appearance 



Fig. 46 Loganograptus logani Hall. Enlargement of branch. Deep kill. x5.25 



of fifth dichotomies on some of the branches results in variations in the 

 number of the branches, commonly ranging in our material between 13 and 

 25. All dichotomy takes place ^vithin 5 mm from the sicula, or within 

 the secondary disk. Branches of the last order ver}' long (7^ inches and 

 more according to Hall). Branches straight, narro^v, of uniform width 

 (.8 mm wide). Thecae numbering 8 to 10 in 10 mm, short, about three times 

 as long as wide, in contact for about half their length, inclined at 30°, their 

 outer margins very slightly concave, the apertural margins straight and 

 inclined to the axis of the branch under an angle of 150°. Large secondary 

 (central) disk pi'esent in larger specimens. 



Position and localities. In graptolite bed 2 (Tetragraptus zone) 

 occur fi'agments of branches which may belong to this species, but no 

 proximal parts wei'e noticed. In graptolite bed 7 (zone of D i p 1 o - 

 g r ap t u s dent a t u s ) Avere found the specimens reproduced on plate 

 9, figures 3-6. Hall reports the species from the Point Levis beds ; but 



