62 TKENTON PERIOD. 



CHAPTEE V. 



TRENTON PERIOD. 



RADIATA. 



Class HYDROZOA. 



Order HYDROIDA. 

 Family GRAPTOLITID^. 



Genus GRAPTOLITHUS Liunteus, 1736. 



Subgenus CLIMACOGRAPTUS Hall, 18G5. 



Graptolithus (Climacograptus*) ramulus White. 



Plate IV, fig. 3 a, h, and c. 



GraptoUtMis [CUmacofiraptus) ramulus White, 1874, Exp. & Snrv. west 100th Merid., 

 Pi'cliiii. Rep. luvert. Foss., 13. 



Stipe slender, bifurcating; bearing cells upon both edges below the 

 bifurcation and upon one edge only (the outer) above that point, so that 

 each series of cells is continuous from the common, proximal, extremity to 

 the distal extremities of the branches respectively. The body of the stipe 

 throughout is moderately thin and flat, but the cells are inflated so that 

 their transverse diameter is considerably greater than the thickness of the 

 stipe ; cells moderately large, each beaiing upon its outer wall about niid- 



*I am incliueil to think that the two groups into which Professor Geinitz has divided his genus 

 Cladograpsus should be designated by separate generic or subgeneric names. In that case, it seems proper 

 that his first group should retaiu the name Cladograpsm^, which would replace Climacograptus of Profes- 

 sor Hall, while the second group seems to .agree with Didijmograpsus of Professor McCoy. Possibly, how- 

 ever, the peculiar character of the colls of the species above described may hereafter require a new generic 

 designation. 



