20 



BULLETIN 65, UNITED STATES NATIONAL MUSEUM. 



After quoting Hall's description of D. gracile, Spencer says of the 

 present form : 



In this species the brancbos are imicb more slender tbau in D. rctiformc, 

 averaging about half a millimeter in breadth and twice that distance apart. 

 The branches are regularly arranged and form fan-shaped fronds, but many 

 specimens indicate the cyathiform structure while living. Though the margins 

 are generally even, yet in one fine specimen the terminations of the branches are 

 irregular. The fronds converge to what Is evidently a noncelluliferous radicle, 

 and in size the finest specimens are as much as 10 cm. high and 0.5 broad. 



Figs. 21, 22.- 



-DlCTVONEMA CKASSIBASALE, NEW SPECIES. TWO KATHEU SMALL RHABDO- 

 SOMES STIOWINi; THE FKOXIMAL PORTION. 



The transverse filaments, which are noncelluliferous, are from four to five 

 times as far apart (sometimes much farther) as the branches; or are frequently 

 obliterated, or almost so. The textui'e is corneous. 



The celluliferous structure is shown in very few specimens. However, one 

 specimen in particular, which I obtained from Mr. A. E. Walker, of Hamilton, 

 removes all doubt as to the character of the cellules. On one side of the branch 

 there is a slender solid axis, in the other there are inserted cylindrical calycles 

 which penetrate the common canal (or coenosarc) almost to the axis. The cells 

 have their own distinct cell walls; they are cylindrical in form, about 0..") nmi. 

 long and 0.35 mm. in diameter. The portion of the cell towards the orifice 



