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NEW YORK STATE MUSEUM 



preservation we have also largely drawn upon it for illustration after careful 

 comparison with Lapworth's type material from Stockport, of which we 

 have also figured the most important forms. 



Description. The branches of the rhabdosome grow to a great length, 

 fragments of 175 to 200 mm being quite common; they are characteris- 

 tically twisted and bent in all possible directions [see pi. 1 9, fig. 8], the proximal 

 part forming a small rectangular axil (^first angle of divergence 270 ) with 



^5533^^3^^^ 



Fig. 223-28 D i cell o grapt 11 s gurleyi Lapworth. Fig. 223, 226 Lapworth's original manuscript figures (speci- 

 mens enl. x 6%). Fig. 224 Sicular portion of a pyritized specimen. The draftsman lias copied the camera drawing 

 incorrectly, the first thecae connecting in front of the sic 11 la; (obverse view). Fig. 225 Sic 11 la r portion with stronger \ ir- 

 gella and lateral spines. Fig. 227, 228 Portions of well-preserved mature branches, (x 5.) See afci text figures 45, 46, 206 



slightly concave sides, which as a rule is followed by gently convex curves 

 of the branches. The latter grow in loose, opposite turning spirals and 

 therefore frequently describe the figure 8 and bear the thecae alternately 

 on opposite sides of the branches [see "Remarks"]. Branches thin, begin- 

 ning with a width of .5 mm and soon attaining a uniform width of .7 to .8 

 mm, which is maintained in the longest branches. Axil wide, the first two 



