2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 



of the interstitial tissue that the remaining portion is left as a net- 

 work of fibers. The same thing happens in algae like Dictyoneuron 

 calif ornicum Ruprecht, whose broad leaf -like thallus bodies, provided 

 with a reticulate system of strengthening ribs, upon decay form 

 reticulate masses of fibers. Dr. H. D. House, State botanist of New 

 York, informs me that such algal remains are verj'^ common along 

 seashores. 



It would be quite possible to refer this form to either Chlorodictyon 

 or Dictyoneuron if it were not for the fact that one of the specimens 

 retains a broadly oval, brownish, carbonaceous film within the net- 

 work of fibers, making it probable that the form had a continuous 

 thallus expansion, a feature that would distinguish it from either 

 genus. (See pi. 2, fig. 3.) 



Description. — Thallus oval to broadly flabelliform — attaining in 

 the largest specimen, not wholly preserved, a width of 5 cm. and a 

 height of 4 cm. — strengthened by a close network of supporting ribs 

 or fibers, which, as a rule, are the only parts preserved. These fibers 

 are for the most part entirely smooth and range in width from 0.25 

 mm. to 0.5 mm. In some portions pores are present, which, since 

 they lack a regular arrangement and are the same size as the grains 

 of the rock, are probably not a part of the organic structure but are 

 merely due to the rock texture. The arrangement of the fibers varies 

 from very irregular meshes in some portions to quite regularl}' rec- 

 tangular meshes in others. 



Since the bases of all specimens are broken, no rhizoids have been 

 observed; nor has anything suggesting sporangia been seen. 



Occurrence. — Middle Cambrian, Burgess shale (Loc. 35K), Bur- 

 gess Pass, near Field, British Columbia. 



Holotype and paratypes. — U.S.N.M. No. 83483. 



Remarks. — ^Although we have compared the organism here de- 

 scribed with Chlorodictyon., one of the Caulerpaceae, and with Dic- 

 tyon£uron, one of the Laminariaceae, no definite characters that 

 would permit one to refer the fossil to either of the two families 

 have been noted. We consider it probable, however, that if the fossil 

 is an alga it must belong to one of these two families, which are so 

 prominent in the marine flora of to-day. 



H . DROZOA 



CHAUNOGRAPTUS SCANDENS, new species 



Plate 2, Figures 4 to 6 ; Plate 3, Figure 3 ; Plate 4, Figure 1 



GroujDed about a specimen of the sponge Tupoia lineata Walcott 

 are some rhabdosomes of a " graptolite " that quite obviously used the 



