920 CONTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



Spines of ovary and flower tube short and stout, the sur- 

 rounding liairs short. 

 Central spines none. 



Stems cylindric 25. E. rigidissimus. 



Stems globular 26. E. weinbergii. 



Central spines present 27. E. pectinatus. 



Areoles nearly circular, not so closely set ; spines never pectinate. 



Ovary strongly tuberculate 30. E, ch.lorophthalm.us. 



Ovary not strongly tuberculate. 

 Flowers small, 2.5 to 5 cm. long. 



Plants strongly angled ; flowers pinkish__31. E. knippelianus. 

 Plants not strongly angled ; flowers purple. 

 Central spines none. 



Spines 3 to 5 ; flower tube and ovary without long wool 



from the areoles 32. E. pulchellus. 



Spines 6 to S; flower tube and ovary bearing long cob- 

 webby wool from the areoles 33. E. amoenus. 



Central spines 1 or more. 



Central spine one 34. E. palmeri. 



Central spines several, much elongate, dagger-like. 



35. E. brandegeei. 

 Flowers large, 6 to 12 cm. long. 



Central spines none 36. E. hempelii. 



Central spines present. 

 Central spine solitary, rarely 2. 



Spines red at base 37. E. merkeri. 



Spines not red at base. 



Plants stout, erect 38. E. fendleri. 



Plants weak, becoming prostrate_39. E. enneacanthus. 

 Central spines several. 

 Spines not white. 



Spines yellowish brown to red 40. E. engelmannii. 



Spines bluish to blackish 41. E. sarissophorus. 



Spines usually white or straw-colored. 



Ribs 7 to 9 42. E. dubius. 



Ribs 11 to 13. 



Flowers campanulate 43. E^ conglomeratus. 



Flowers short-funnelform 44. E. stramineus. 



1. Echinocereus delaetii Giirke, Monatsschr. Kakteenk. 19: 131. 1909. 

 Cephalocereus delaetii Giirke. Monatsschr. Kakteenk. 19: 116. 1909. 

 Known only from the Sierra de Paila, north of Parras, Coahuila. 



Low, 10 to 20 cm. high, densely cespitose, completely hidden by the long 

 wliite curled hairs ; ribs indistinct ; areoles closely set, bearing 15 or more 

 white reflexed hairs 8 to 10 cm. long and a few stiff reddish bristles; flowers 

 appearing near the top of plant; perianth segments pink, oblanceolate, acute; 

 ovary covered with clusters of long white bristly spines. 



In appearance this resembles small plants of Cephalocereus senilis. 



2. Echinocereus scheeri (Salm-Dyck) Riimpler; Forst. Handb. Cact. ed. 2. 801. 



1885. 

 Gereus scheeri Salm-Dyck, Cact. Hort. Dyck. 1849. 190. 1850. 

 Chihuahua, the type collected near the City of Chihuahua. ' 



