40 BULLETIN 115, UNITED STATES NATIONAL MUSEUM. 



With 10 to 20 arms — Continued.^ 



Calyx large to medium size. etc. — Continued. 



Ridges on radial series more or less continuous; central 

 nodes on RR and iBr not prominent, or absent. 

 Surface ornament chiefly by rows or clusters of pus- 

 tales or wrinkles more or less radiately arranged. 

 Very large and massive: surface coarsely 



wrinkled />. m(\nnifinn<. 



Less massive; calyx broad; radial ridges low, 

 rounded, not enlarging at the centers; orna- 

 ment by sinuous radiating lines. 



Tegmen low and broadly lobed D. rnrporofW'. 



— var. decoratus. 

 — welleri. 

 Surface ornament by distinct radiating striae tend- 

 ing to form geometri(>al figTires. more or less com- 

 bined with scattered pustTiles. 

 Calyx broad and low. 



Tegmen low, smooth, obscurely lolled, 



plates indistinct T>. hnJiarunsis. 



— preciopus. 

 Tegmen rugose, distinctly lobed, plates well 



defined, with small nodes or pustules D.fjrann. 



— corporosus, var. cnncinniis. 

 Calyx high. 



Tegmen "s^entricose or high conical, strongly 

 lobed, more or less covered with small 



nodes or pustules D. linrnhfnfs. 



^sacculus. 



— salebrosus. 



• — charlestownensis. 



— cistula. 



— asper. 



— eicosidactyliis. 



— sprinceri. 



Ridges on radial series more or less discontinuous; nodes 



on radials and iBr prominent. 



Surface ornament by radiating striae, usiially dis- 

 tinct, forming geometrical figiires. 

 Tegmen ventricose, lobed, with more or less 



small scattered spiuns or shai'p nodes D. hcUuhis. 



— basilicue. 

 — nodnliferus. 

 Tegmen flatter, but little lobed, and witlioul 



nodes or spines />. nodos^us. 



— tuberculatiis. 



— multinodosus. 



— elegantuhis. 



Tegmen lobed, with strong nail-head spines D . fungijerua . 



As of the 02 species and varieties described froxn the Hamilton 

 over 60 per cent are considered to be synonyms, it will be convenient 

 to treat them by gi-oups, following the arrangement in the foregoing 

 kev. 



