242 REPORT ON THE STATE CABINET. 



into two ; and in the separated stipes it is impossible to know if there 

 have been two, four or eight in the entire individual. With regard to 

 those fronds which are repeatedly dichotomous, forming the genus 

 DiCHOGRAPTUS, of wliich the distinguishing character is the central 

 "corneous plate which envelopes all the lower part of the branches," 

 we may remark, that we have three or four species of the four-stiped 

 form, or " Tetragraptus " with the central corneous plate; while we 

 have four species which are not known to possess it. Of the two eight- 

 stiped species known, one has the central corneous plate or disc, and the 

 other was probably destitute of such an appendage. In G. logani, with 

 its numerous simple stipes, the central corneous plate is usually present, 

 though not in all examples ; while G. multifasciatus , with more numerous 

 simple stipes than G. logani^ is not known to have a central corneous disc, 

 and from its mode of growth, probably never possessed such an append- 

 age. From the irregularity of growth in the G. abnormis, I infer that 

 there was no central plate. 



In all the properly -branching species where the initial point is known, 

 as in G.flexilis, G. rigidus, and G. milesi, no such central plate has ever 

 been seen ; nor has it been shown in any European species, so far as I 

 Icnow. Those with the " fronds repeatedly dichotomous," similar to the 

 one originally proposed by Mr. Salter* as the type of Dichogbaptus, 

 are not known to possess the central corneous disc. 



Although entirely willing to accept and adopt such subdivisions of the 

 graptolites as will aid in determining their zoological character and rela- 

 tions, their geological value, or indications of differences in mode of 

 development, I do not appreciate the force and value of these proposed 

 generic subdivisions for the two, four and eight-stiped species, or the 

 presence or absence of a central corneous disc as indicating generic dis- 

 tinctions ; since it is impossible to obtain any aid from such designations 

 for the references of the numerous fragments which are the ordinary 

 form and condition in which we find the graptolites, and in which they 

 must generally be studied. 



The form, mode of growth, and arrangement of cellules in all these 

 several proposed genera, are so identical in plan as to afford no means for 

 generic separation ; and although the same is true of the properly ramose 

 forms, yet I conceive it might have been convenient to adopt a term 

 (Dichogbaptus or Cladogbaptus) indicating the ramose character of the 



* Otologist, Vol. 4, p. 74, 1861. 



