90 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



DICTYOPHYTON RUDE ( n. s.). 



PLATE V. FIG. 3. 



A STRONG flattened stem (not unlike fig. 3 of Plate iv), with coarse 

 elevated cancellating ridges and intermediate longitudinal and 

 transverse fine strise. 



The fragment is compressed, having a length of five inches with a dia- 

 meter of two and a half inches. In the evenness of the finer intermediate 

 striae, and the greater strength of the coarser ones, it difi"ers from the stems 

 referred to D. neioberryi. 



The figure represents a small portion of the surface. 



Formation and locality. In the Chemung group, at Little-Genesee, Al- 

 legany county, N.Y. 



DICTYOPHYTON FENESTRATUM ( n. s.). 



PLATE III. FIG. 4. 

 For description, see the Explanation of the Plate. 



DICTYOPHYTON ANNULATUM ( n. s.). 



PLATE III. FIG. 3. 



Cylindrical annulated stems, without nodes, and having a finely 



reticulated surface. 



A fragment about two inches in length, with a similar one by the side of 

 it, are all that have been seen of this species. It has surface-markings not 

 unlike the preceding species, but not so regularly alternating in size, while 

 the annulated stem is distinctive. This form is intermediate to the nodose 

 and smooth-stemmed species. 



DICTYOPHYTON TUBEROSUM. 



PLAE III. FIG. 1. 

 Hydnoceras tuberosum : Conrad, Jour. Ac. Nat. Sciences, VoLviii, p. 267, & pL 16, f. 1. 



Stem hollow, obconical, rapidly expanding above. Entire surface 

 reticulate by longitudinal and transverse strise, and marked by 

 several series of longitudinal subangular nodes, which are con- 

 tinue*d across the intermediate space by a sharp slightly elevated 

 ridge. 



The original specimen, which is imperfect, has a length of a little more 

 than five inches, showing five ranges of nodes ; while another imperfect 

 specimen has a length of seven inches, with the same number of ranges of 

 nodes. A fragment of a larger individual, with three ranges of nodes, has 

 a length of five inches, with six or seven nodes in each range. 



Geological formation and locality. In the sandstone of the Chemung 

 group at Howard and Addison, Steuben county. 



