ID NEW YORK STATE MUSEUM 



The three species of Buthotrephis from the Eurypterus beds 

 appear to us as the final stage of the development which the sessile 

 graptolites of the order Dendroidea were taking in the Clinton- 

 Niagara stages and which is most distinctly expressed in the 

 genera Palaeodictyota of our Clinton and the strange graptolite 

 fauna from the Niagaran dolomites at Hamilton, Ontario. In that 

 fauna there have been described by Gurley and Bassler species of 

 as strangely algal aspect as our Buthotrephis unhesitatingly as 

 graptolites because of their association and of the fact that wherever 

 the stipes were sufficiently well preserved they exhibited a distinct 

 graptolite structure. The marine conditions under which these 

 dolomites were deposited and these graptolites existed were to all 

 appearances similar, though not nearly so pronounced as those 

 under which the eurypterids flourished, and it is a fair conclusion 

 that the three species of Buthotrephis represent the extreme adapta- 

 tion to these lagoon conditions. This, finds its strongest expression 

 in the broad expansion (in the compressed condition, see below) of 

 the stipes and the resulting algal aspect. 



While we thus fully recognize the distinct algal habitus of 

 Inocaulis lesquereuxi and consider it still possible that 

 it may prove an alga, we see, on the other hand, in the absence of 

 any observed fructifications, its composition of fine tubes emptying 

 on the surface, and its connection with true graptolites by preceding 

 gradational stages fair evidence for its graptolite nature. 



Inocaulis lesquereuxi consists of numerous long, 

 cylindrical erect rhabdosomes or polyparies (about 20 cm long and 7 

 to 10 mm wide), which originate to the number of about 8 to 10 

 from a common base, are sparingly dichotomous (mostly undivided, 

 bifurcating once, or twice at the most), gradually widening toward 

 the apex, which is well rounded, somewhat club-shaped ; polyparies 

 straight or slightly undulating, consisting of ropelike, twisted, thin 

 tubes which open perpendicularly to the general surface in circular 

 pores that are densely crowded (about five in 1 mm linear) and 

 separated by intervals not larger than their own diameters. The 

 width of the tubes is but one-twentieth mm. 



Remarks. The rhabdosomes of this graptolite are so completely 

 flattened that they at first glance suggest a ribbonlike shape. The 

 absence of twisted rhabdosomes, however, as well as the indication 

 of a bursting of the cylinders along the edges and the crowding of 

 the pores near the edges in other branches, indicate that the 

 rhabdosomes were cylindrical in shape, as the twisted mass of 

 tubules opening on the entire surface would require. 



