1 50 The Atncricaii Geologist. September, looo 
Decadocriniis tumidiihis M & G. 
Fig. 5. Specimen showing part of ventral sac perforated with 
li 
pores — i 
I 
Fig. 6. One plate and parts of connecting plates from the same 
specimen, showing large elliptic pores in median plate, 
and smaller round ones in those on either side. Here 
the pores lie in the ridges along the radial lines \ 
Scaphiocrinus tmicus Hall. 
Fig. 7. Plates of the ventral sac, two of them on edge. The 
pores lie in the ridges at the sides of the plates, not at 
the angles; and are represented by grooves passing over 
the edges of the plates \ 
Scytalocriniis hoveyi Worthen. 
Fig. 8. Plates of ventral sac in similar position to those of fig. 7. 
Pores represented by more numerous slits or grooves 
passing across the edges of the upturned plates 1 
Scytalocriniis validus Worthen. 
Fig. Q. Specimen with ventral sac nearly complete, showing 
pores on the suture lines at the middle of the sides of 
the plates; surface smooth j 
Fig. 10. One plate of the same specimen \ 
Aiilocriniis agassizi W & Sp. 
Fig. ri. Specimen showing nearly entire ventral sac, with anal 
tube broken. Pores at the middle of the sides of the 
plates I 
Fig. 12. Single plate of the same specimen \ 
Scytalocriniis va7i hornet Worthen. 
Fig. 13. Specimen preserving ventral sac perforated by small 
pores at middle of plates. Surface perfectly smooth \ 
Fig. 14. Single plate of same specimen \ 
Scapliiocriniis inissouricnsis Shumard. 
Fig. 15. One plate of ventral sac, with connections, showing the 
slits or fissures passing from plate to plate \ 
Scaphiocrinus swallovi M & W. 
Fig. 16. One plate of ventral sac, with parts of contiguous plates, 
showing the large elongate pores in depressions at mid- 
dle of sides \ 
