964 CONTRIBUTIONS FROM THE NATIONAIi HERBARIUM. 



Flowers yellow or white. 



Tubercles very large, broader than high 14. C. bumamma. 



Tubercles of medium size, if large longer than broad. 



Plants large, often 8 cm. in diameter ; seeds 3 mm. in diameter. 



15. C. robustispina. 

 Plants smaller ; seeds 2 mm. or less in diameter. 

 Central spines usually wanting. 



Secondary cluster of spines developed in upper part of areoles 



and connivent at top 16. C. connivens. 



Secondary cluster of spines not developed. 



Spines pectinate 17. C. pectinata. 



Spines not pectinate. 

 Spines 14 or more. 



Spines slender, with long black tips 18. C. nickelsae. 



Spines rather short, with light tips. 



Spines subulate 19. C. compacta. 



Spines acicular 20. C. radians. 



Spines fewer than 14. 



Spines slender and weak 21. C. sulcolanata. 



Spines not slender 22. C. retusa. 



Central spines one to several. 



Central spines strongly hooked 23 C. palmeri. 



Central spines straight, or at most curved. 

 Central spines more or less curved. 

 Central spine one. 

 Radial spines nearly as long as the central. 



24. C. cornifera. 

 Radial spines about half as long as the central. 



25. C. salm-dyckiana. 

 Central spines several. 



Radial spines 20 or more 26. C. pallida. 



Radial spines 12 or fewer 27. C. pycnacantha. 



Central spines straight. 

 Radial spines of two kinds (to be looked for here). 



5. C. poselgeriana. 



Radial spines of one kind 28. C. durangensis. 



Outer perianth segments ciliate. 



Inner perianth segments very narrow 29. C. neomexicana. 



Inner perianth segments narrowly lanceolate 30. C. aggregata. 



1. Coryphantha macromeris (Engelm.) Lem. Cact. 35. 1868. 



Mammillaria macromeris Engelm. in Wisliz. Mem. North. Mex. 97. 1848. 



Mammillaria heteromorpha Scheer; Salm-Dyck, Cact. Hort. Dyck. 1849. 128. 

 1850. 



Mammillaria dactylithele Labour. Monogr. Cact. 146. 1853. 



Chihuahua to Zacatecas. Texas and New Mexico ; type from Dona Ana, 

 New Mexico. 



Plant branching at base, often many-headed, up to 20 cm. long; tubercles 

 large, soft, loosely arranged, elongate, 12 to 30 cm. long, grooved on upper 

 side about two-thirds their length ; spines 10 to 17, slender, the radials white ; 

 central spines several, black, the longer ones 5 cm. long ; flowers large, purple, 

 6 to 8 cm. broad; scales on flower tube ciliate; ovary bearing a few scales 

 with hairy axils; fruit 15 to 25 mm. long; seeds globose-obovate, brown but 

 sometimes described as yellow, smooth. 



