EXPLANATIONS OF TLATE I, continued. 

 Germs of Graptolites. 



Figures 12, 13, 14, 16, 17, 18, 19, are germs of Graptoltes enlarged to six diameters. 

 Fig. 12. A germ of a biserrate form, before the cellules have assumed distinctive shape. 



The axis is extended, and the common envelope spreads on both sides in the 



lower part; the coenosarc embracing the lateral processes, which are seen at 



the base of most of the diprionidian forms, and extending along one side of 



the axis above. 

 " 13. A form similar to fig. 12, a little further advanced, where the lower cellules 



have begun to assume their proper form. 

 '' 14. Another form of germ resembling G . ciliatus ; the ciliated processes are visible 



beyond the limits of the sac, but the cellules appear not to have assumed 



definite form. 

 " 15. A young individual of G. ciliatus (natural size). 

 " 16. A discoid germ. This may be the central disc of a compound form of Grapto- 



lithus [?]. 

 " 17. A germ showing the common body extended on the two sides of the axis, but 



without any visible or apparent cellules. 

 '^ 18. A germ where the common body or sac is much expanded on the two sides of 



the axis, and the central portion is apparently becoming more solid. 

 ^' 19. A germ where the solid axis is on one side ; the species probably belongs to 



the monoprionidian type. 



Eetiolties venosus. 



(Paleeontology ot New- York, Vol. il, page 40.) 

 The figures are enlarged to nine diameters. 

 Fig. 20. The exterior of the convex (?) side, showing the external axis and cell-parti- 

 tions, with the intermediate reticulate texture. 

 " 21. Another view, apparently from the interior, showing an undulating or zig zag 

 axis, with cylindrical processes extending to the margins, and short, apparent- 

 ly broken processes directed obliquely upwards. The reticulate stricture is 

 not essentially different from that of the other side. 



