THE FOSSIL CRINOID GENUS DOLATOCRINUS AND ITS ALLIES. 27 



ONONDAGA SPECIES. 



[Valid species in italics; synonyms in roman.] 



With 10 arms. 

 Calyx small. 



High cup-shaped, with broadly truncate base; central nodes 

 small. 



Radiating striae few and coarse. 



Tegmen low ; pinnule openings prominent. 



Sides of cup nearly vertical D. lacus. 



— approximatus . 

 Sides of cup sloping inward from broad base. . D. pyramidaius, 



new species. 

 Depressed basin-shaped, sides sloping outward; broadly 

 curving base with small pit. 

 Radiating striae or wrinkles fine and numerous; radial 



ridges low or wanting; no nodes. D. ornatus. 



Surface smooth; tegmen and cup evenly rounded to a 



globose contour D. rotundus, new species. 



Calyx medium sized. 



Doubly conical, with broad base; sides sloping at wide angle 

 to arm bases; sharp median ridge on radials and IBr. 

 Radiating striae coarse or wanting. 



Tegmen rather low D. spedosus. 



Radiating striae line and sharp. 



Tegmen higher; pinnule openings prominent I), marshi. 



Calyx large, subhemispheric. 



Base truncate, deeply excavate, involving all of radials; 

 iBr single, angular above, followed by two plates which 

 are pinnulars; median ridge on radials and IBr obtuse 

 or absent; surface of cup-plates strongly wrinkled. Teg- 

 men high convex; pinnule openings large and numerous. . L>. grandis. 



— excavatus. 

 — A'ar. unicarinatus. 

 — fossatus. 

 With 20 arms. 

 Calyx large. 



Base shallow concave, with small pit; cup-plates orna- 

 mented with fine radiating striae; median ridge on radial 

 series strong, keel-like. 

 Tegmen moderately convex ; pinnule openings few and 

 prominent. 

 Median ridge confined to radials and IBr. Teg- 

 men bearing strong spines D. spinosus. 



— curriei. 

 Median ridge continuing to arms. Tegmen without 



strong spines D. insuetiis. 



Insufficiently defined ; similar to spinosus in dorsal 



cup, but tegmen unknown D. lamellosus. 



Base broad and flat, with shallow pit not including radials; 

 surface smooth, small node or spine on IBr, exceptionally 



a keel-like ridge D. major. 



18R0cSl— 21 3 



