290 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



Genotype and only knoum species. — Ptychocladia agelhis new 

 species. 



PTYCHOCLADIA AGELLUS new species 



(Plate LXVII, 10 (part), 13) 



Beginning with a comparatively strong, curved stem, 0.2 mm. to 

 0.5 mm. in width, the colony continues its growth by addition of 

 frequently dividing and coalescing depressed convex, branches which 

 increase in width from o.i mm. to 0.2 mm. or more, until an irreg- 

 ularly cribrose expansion, 3.0 mm. to 5.50 mm. in width, is produced. 

 Basal stem and branches with transverse wrinkles, apparently com- 

 posed of structureless, cemented, calcareous grains, which occasion- 

 ally appear to have been combined so as to leave minute pores 

 between them. 



The minute structure of these fossils is very obscure, and their 

 systematic position so doubtful that we are scarcely willing to hazard 

 an opinion. Possibly they are algse, or, if their branches are tubular,* 

 a point we did not succeed in determining, they may be related to 

 some of the preceding forms. Again, they may prove to belong to 

 some peculiar type of Foraminifera. Of these various possibilities, 

 the first strikes us as the most plausible, though we are not by any 

 means prepared to express a decided opinion. 



Occurrence. — Upper Coal Measures, near Springfield, 111. Asso- 

 ciated with Allonema f minutiim. 



Cat. No. 43,123, U. S. N. M. 



EXPLANATION OF PLATES 

 Plate LXV 

 (With the exception of figures 11 to 13, allof the illustrations on this plate 

 were reproduced from rather crude tracings of previously published figures, 

 and reduced one-third in the reproduction. Figures i to 8 are of recent 

 species from Hincks' British Marine Polyaoa, figures 9 and 10 from Nicholson 

 and Etheridge's work on Ascodictyon, and figure 14 from a paper by 

 Whiteaves.) 



Fig. I. ALtea anguina Linnjeus. Showing zooecia arising from the creep- 

 ing stem, X 16. 



2. Aitca truncafa (Landsborough). A portion of the creeping base, 



X 16. 



(Figures i and 2 are introduced for comparison with Allo- 

 nema and Rhopalonaria). 



3. Cylindrcccium dilatatum Hincks, X 16. 



4, 5. Vesicularia spinosa Linnaeus, X 16 and X 28, to be compared with 

 Vinella and Hetcronema. Figure 4 represents the terminal por- 

 tion of a branch from which most of the zocecia have been 

 stripped. 

 6. Valkeria uva Linnaeus. Erect form, X 16, Allonema and Asco- 

 dictyon are to be compared with this genus. 



