400 



NEW YORK STATE MUSEUM 



The figures here given serve to illustrate the various states of preserva- 

 tion of the rhabdosome, figure 348 representing that which led to the first 

 misconception. 



It is remarkable how much more frequently this form is found in whole 

 colonies than all the other diplograptids, among which synrhabdosomes 

 are most astonishingly rare. The writer has seen synrhabdosomes of (i. 

 eucharis from the type locality, from Dolgeville, where they were quite 

 common in one place and from other outcrops in the Mohawk valley ( Hol- 

 land Patent, Canajoharie), Waterford and Millers brook and Kent brook 

 near Floyd, N. Y. (the latter in Amer. Mus. Nat. Hist.). This frequent 

 preservation of the whole colon)' is evidently due to the smallness of the 

 same and the shortness of man)' nemacauli. 



G . eucharis is readily distinguished from all other associated forms 

 l)) r its small size, the extremely close arrangement and broad, short form of 

 the thecae. The development of the spines seems to have been subject to 

 considerable variation ; they were found to be of remarkable length and 

 curved in some localities and horizons, as at the Rural cemetery and again 

 but inconspicuous and straight in others, as at the dam in Mechanicville. 



CLIMACOGRAPTUS Hall. I 865 



This genus was proposed by Hall with C . b i c o r n i s as type. The 



original description is : 



Simple stipes with subparallel margins, having a range of cellules on 

 each side; axis filiform; cellules short and square; apertures apparently 

 excavated in the margin of the stipe, and transversely oval or subquadrate ; 

 cell denticles or appendages, if present, usually on the upper side of the 

 aperture. 



The principal character of Climacograptus is to be seen in the peculiai 

 geniculation of the thecae which in their proximal part are attached parallel 

 to the axis, then turn outward and finally again become parallel to the axis 

 thereby placing the aperture into a more or less deep, transverse excava- 

 tion between two successive thecae. As the earlier ami more primitive 

 species (as C. pun gens and C. putillus) apparently are those to be 

 regarded in which the middle part is still obliquely instead oi rectangularly 



