18 



a substance unfavorable to the preservation of the cellules or 

 of the finer markings of the surface. 



In the form and proportions of the cellules and the greater 

 proportional width of the connecting filaments, this speciee 

 differs from any of those described. 



Geological formation and locality. In the Trenton limestone 

 of the Fox river, near Appleton, Wisconsin. I am indebted 

 to Prof. R. Z. Mason, ot the Appleton University, for the 

 specimen. 



Near the base of the Trenton limestone at Platteville and 

 other localities, there are some slaty layers completely charged 

 with fragments of organic bodies which have the appearance, 

 color and texture of the Graptolitidae. In 1860 I collected 

 from this locality numerous specimens of these shales, and I 

 am also indebted to Mr. J. D. Whitney (lately of the Wis- 

 consin Survey, and now Geologist of California) for a piece 

 of limestone from the same neighborhood, containing some 

 of these forms in a more complete condition. Since that 

 period, large numbers of specimens have been collected, show- 

 ing an abundance of these fragments, quite unprecedented in 

 any locality of Graptolites, which I have examined. Many of 

 these fragments are long and slender, and have evidently been 

 floated and macerated before being imbedded. Some of them 

 are twisted together, either from their natural relations, or, 

 what appears more probable, by the action of the waves before 

 these forms were finally thrown down upon the muddy bottom. 

 A few fragments of Trilobites and shells, with valves of Lep- 

 erditia, occur in the same association. 



Notwithstanding this abundance of fragments, I have thus 

 far been unable to make out more than a single form in & 

 condition to be satisfactorily described. This form is gene- 

 rally distinct from any heretofore described, so far as I am 

 aware. It consists of a long principal or central stipe, with 

 diverging branches, closely arranged and often recurved. The 

 stipes, so far as observed, are simple and linear, and the 

 branches are simple and linear, terminating in a thickened 

 lanceolate extremity. The main stipe is distinctly marked by 

 round or oval spots, representing the cellules; the branches 

 are striated, and with sometimes some obscure marks of cel- 

 lules. For this form I propose the Generic name of Butho- 

 grapius. 



GENUS BUTHOGRAPTUS, (nov. gen.) 



Generic character. Frond consisting of a central stipe with 

 closely arranged lateral branches, which are flexuous or re- 



