42 THE CACTACEAE. 



Echinocactus radiatus Hortus Belg. was referred as a synonym of Mainiuillaria 

 pycnacantha by Pfeiffer (Enum. Cact. i8o. 1837). 



Illustrations: Nov. Act. Nat. Cur. 16: pi. 17; Loudon, Encycl. PL ed. 3. 1379. f. 19387; 

 Abh. Bayer. Akad. Wiss. INIunchen 2: pi. 3; Pfeiffer and Otto, Abbild. Beschr. Cact. i: 

 pi. 26; Curtis's Bot. Mag. 69: pi. 3972, as Mammillaria pycnacantha. 



Figure 39 is reproduced from the first illustration cited above; a spine-cluster is also 

 shown. 



28. Coryphantha echinus (Engelmann) . 



Mammillaria echinus Engelmann, Proc. Amer. Acad. 3: 267. 1856. 



Cactus echinus Kuntze, Rev. Gen. PI. i: 260. 1891. 



Mammillaria radians echinus Schumann, Gesamtb. Kakteen 496. 1898. 



Solitary-, globose to subconic, 3 to 5 cm. in diameter, almost hidden under the closely appressed 

 spines; areoles orbicular or a Uttle longer than broad; radial spines numerous, white, 10 to 16 mm. 

 long; central spines 3 or 4, the 3 upper erect or connivent over the apex, the lower one porrect on 

 side of plant, erect near top, subulate, straight, 1.5 to 2.5 cm. long, often blackish; flowers 2.5 to 

 5 cm. long, yeUow; outer perianth-segments linear-lanceolate; inner perianth-segments 20 to 30, 

 narrow; stigma-lobes about 12; fruit oblong, 12 mm. long. 



Type locality: On the Pecos River, Texas. 



Distribution: Western Texas. 



The flowers with the type plant seem to have been shriveled, for Engelmann describes 

 them as large, apparently about i '-2 or 2 inches long; in a later description he states that 

 they are yellow. This species is ven,^ rare in collections and we have seen no flowers of it. 

 All the illustrations cited below are based on the figure in the jNIexican Boundary Stu^ey. 



The name Coryphantha echinus occurs in C. R. Orcutt's Circular to Cactus Fanciers, 

 1922. 



Illustrations: Cact. Mex. Bound, pi. 10; Diet. Gard. Nicholson 4: 562. f. 32; Suppl. 

 515. f. 549; Watson, Cact. Cult. 157. f. 59; ed. 3. f. 37; Forster, Handb. Cact. ed. 2. 404. f. 

 43 ; Blanc, Cacti 68. f. 1228, as Mammillaria echinus; Schelle, Handb. Kakteenk. 240. f. 159, 

 as M. radians echinus. 



Figure 316 is from a photograph of a plant obtained by George L. Fisher near Langtry, 

 Texas, in 1922. 



29. Coryphantha diu'angensis (Riinge). 



Mammillaria durangensis Riinge in Schumann, Gesamtb. Kakteen 478. 1898. 

 Plants sohtarj- or in small clusters, short-cyhndric, 10 cm. long or less, somewhat glaucous; 

 tubercles rather prominent, in 5 or 8 series, somewhat compressed dorsallv, ver\' woollv in the axils ; 

 radial spines 6 to 8, acicular, spreading, i cm. long or less; central spine solitary, often erect, those 

 of uppermost areoles connivent, black; flowers verj' small, about 2 cm. long, when fully expanded 

 2.5 to 4 cm. broad; outer perianth-segments dark purple or with only a purple stripe down center; 

 inner perianth-segments cream-colored to pale lemon-yellow; filaments cream-colored, about length 

 of stjde; style and stigma-lobes cream-colored, the latter 5, linear and curved backward; fruit globu- 

 lar, 5 to 8 mm. in diameter, naked, greenish; seeds brown, about i mm. broad. 



Type locality: Villa Lerdo, Durango, Mexico. 



Distribution: Northern Mexico. 



Dr. E. Chaffey has collected this plant for us several times at the type locality, but it 

 does not sun,-ive long under glass. In 191 1 he found a cristate form with the lobes flat- 

 tened Uke the joints of an Opuntia, bearing flowers along the edges. 



This is Mammillaria compressa of Hildmann's Catalogue, according to Schumann 

 (Gesamtb. Kakteen 479. 1898). 



Illustration: Wiener 111. Gart. Zeit. 29: 411. f. 105, as Mammillaria radians. 



Plate v, figitre 4, shows a plant sent by Dr. Chaffey from the type locality in 19 18, 

 which flowered in the New York Botanical Garden, April 8, 1918. Figure 40 is from a 

 photograph of a potted plant sent by Dr. Chaflfey in 1910 which flowered in Washington; 

 figure 41 is from a photograph of another plant sent by Dr. Chaffey in 19 10. 



