GRAPTOLITES OF NEW YORK, TART 1 771 



Tetragraptus pygmaeus sp. nov. 



Page 664 



11 Young rhabdosome showing the long, narrow sicula and the four thecae 



from which the four branches grow. x5 

 12, 13 Obverse and reverse sides of two approximately matured rhabdo- 



somes, x3. 

 14 Mature rhabdosome, reverse side. But two branches are exposed. x7 

 Graptolite bed 2 of the Deep kill section 



Tetragraptus taraxacum sp. nov. 



Page 663 ' 



17 Early growth stage of rhabdosome. Obverse side. x8 



18 Mature rhabdosome. x2 



19 Mature rhabdosome showing the rapid widening of the branches. xS^ 



20 Young rhabdosome, reverse side, further enlarged to show the point of 



origin of the first theca and the bifurcations. x7 



21 Mature rhabdosome showing maximal length of branches observed. 



x2 



22 The original of figure 19 in natural size 



23 Rhabdosome showing the curvature of the branches. x2 



24 Young rhabdosome showing the slender form of the proximal thecae. 



x7 



25 A lateral pair of branches retaining their original angle of divergence. 



x7 



26 Another pair of lateral branches compressed in different directions. They 



show distinctly the outline of the thecae. x7^ 

 Graptolite bed 2 of the Deep kill section 



