I5O NEW YORK STATE MUSEUM 



DICTYONKMA Hall 

 See N. Y. State Mus. Mem. 7, p. 591 



Dictyonema neenah Hall 

 Diet yon em a neenah Hall. Sup't Geol. Sur. AVis. Rep't Prog. 1861. p. 7 

 Dictyonema neenah Whitfield. Amer. Mus. Nat. Hist. Mem. 1895. v - J > l ;t 2 > 



P- 47, pi- 5- fi K- 13 

 Dictyonema neenah Pocta. Syst. Sil. Boheme. 1894. vol. 8, t. 1, p. 193 

 Dictyonema c f. neenah Gurley. Jour. Geol. 1896. 4:81 

 Dictyonema nee n a h Gurley. Ibid. p. 300 



Original description. Frond spreading, infundibuliform, reticulate, the 

 radiating branches slender, direct, a very little undulating, the transYerse 

 connecting filaments more slender than the branches : reticulations quad- 

 rangular or OYal, the length from one and a half to twice the width ; from 

 six to seven and a half in the space of half an inch, and transversely from 

 12 to 14 in the same distance. Serrations or cellules not determined. 



This species is deeply funnel-shaped, the branches but slightly diverg- 

 ing and the intercalated or implanted branches at distant intervals. The 

 matrix is a compact granular limestone, 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 propor- 

 tional width of the connecting filaments, this species 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, 

 of the Appleton University, for the specimen. 



Dr Gurley annotates this form in his manuscript as follows : 



Hall's description and Whitfield's figure cover all essential points. 

 Branches about 30 in 25 mm, 0.3-0.4 mm wide. The dissepiments are 

 mostly 12-16 in 25 mm; usually stouter than the branches, ranging from 

 0.4 to 0.8 mm. They are usually biconcaYe, widening as they approach the 

 branches, thus giving the mesh an elliptic form. The tendency of the dis- 

 sepiments to extend across many branches at the same level (producing a 

 banded appearance) is pronounced. The infundibuliform aspect of the 

 polypary is perfectly evident, the whole lower half being clearly traceable 

 distally under a thin "cliff" of the rock. Though very distinctly defined 

 the branches and dissepiments are only preserved as stains, and no thecae 

 are anywhere visible. 



The most striking features of this species are the great width of the 

 dissepiment, their biconcavity and tendency to occur at regular levels 

 forming continuous broad dark binds across the surface. 



