REPORT OF THE DIRECTOR IQIQ 



253 



graphic processes should be given careful study. The features of 

 the basins are, however, not essentially different from those shown in 

 figure 29 which is of the apotype and photographed without mount- 

 ing. The diameter, distance apart, number on the suture and the 

 shape of the basins should enable one to easily determine this species 

 whether intact, w^eathered or crumbled into separate plates. 



Figures 30-33 show 

 also a detail of very 

 considerable interest. 

 The figures are from 

 four different nega- 

 tives and thus show 

 the feature in different 

 lights. Plate 41 of 

 these figures had at 

 one time a sutural 

 canal near the middle 

 of the suture between 

 it and plate 42. Plate 

 41 seems to have ex- 

 tended this sutural 

 margin a little more 



rapidly than its neigh- ^^^^^ Photomicrograph of tegmei^ of Palaeocystites 

 bor or else it failed to dawsoni BilUngs. xio. Compare with figure 24 



place stereom back of the canal. The result was that this plate 

 had soon surrounded the canal and left the suture without one at 

 this point. It was pointed out on page 199 that such a thing might 

 occur, and in plate 6, figure 3, at c (see also figure 4 of the same 

 plate), we saw a canal nearly so inclosed. This then is a case 

 in which such inclosure did become complete and a perforated 

 plate is the result. 



In figure 26 at 111 we have also a perforated plate, but this is no 

 doubt a normal feature and represents either a hydropore or genital 

 pore. The size of the anus as compared with the mouth is an indi- 

 cation of anal respiration. 



Sigmacystis emmonsi Hudson 



M a 1 o c y s t i t e s emmonsi Hudson. Report of the State Paleontolo- 

 gist for 1903. N. Y. State Mus. Bui. 80, p. 270. 



The species cited above is congeneric with IMa 1 o c y s t i t e s 

 b a r r a n d i Billings but both differ so much from M a 1 o c y s t i t e s 



