58 



THE CACTACEAE. 



typical species of the so-called Mammillaria in its large flowers and black seeds, while from 

 all of these genera it differs in its circumscissile fruit. 



This monotypic genus is named for Dr. Paul Bartsch, curator in the United States 

 National Museum, distinguished in conchology, who has sent us cacti from many out of 

 the way places. 



1. Bartschella schumannii (Hildmann). 



Mammillaria schumannii Hildmann, Monatsschr. Kakteenk. i: 125. 1891. 

 Mammillaria venusla K. Brandegee, Zoe 5: 8. 1900. 



More or less cespitose (as many as 40 stems have been reported in a single cluster), 6 cm. high 

 or less; axils slightly woolly, without bristles; radial spines 9 to 15, stout, 6 to 12 mm. long, brownish 

 above, glabrous; central spines usually i, sometimes 2 or 3, one of these usually hooked; in seedlings 

 10 or II radial spines developing, these spreading, feather-like with long spreading hairs ; in one-year- 

 old plants the spines simply puberulent, all white with brown tips and one central much longer than 

 the others and strongly hooked; flower 3 to 4 cm. in diameter, the segments about 10, lanceolate, 

 acuminate; stamens numerous, erect, shorter than the style; style slender, erect, pale; stigma- 

 lobes 6, linear, green; fruit short, dull in color; seeds usually found in a cup between the tubercles, 

 less than i mm. long. 



Fig. 55. — Bartschella schumannii. 



Fig. 56. — Pelecyphora aselliformis. 



Type locality: Not cited.* 



Distribution: Southern Lower California. 



This species has been rare in collections, but considerable material was collected by 

 Dr. Rose at Cape San Lucas, Lower California, in March 191 1 (No. 16375). Living 

 specimens were sent us from Lower California by Ivan M. Johnston in 192 1. 



Dr. C. H. Thompson writes under date of September 15, 1911, as follows: 



"Your No. 16375, Mammillaria venusla, puzzles me. We received three plants from the New 

 York Botanical Garden. Two are considerably shriveled but are reviving. The third is more plump 

 and shows the vegetation characters better. In these it would readily be taken for Mammillaria, 

 yet there are some appearances of the mamillate Echinocacti. You will observe how commonly 

 adjacent tubercles cohere as in that group of Echinocactus, quite distinct from any Mammillaria that 

 I know. Yet the position of the flower excludes if from Echinocactus. With flower and fruit char- 

 acters you have observed it strikes me as being distinct from either genus." 



* Mammillaria schumannii was described from a cultivated plant, but M. venusla came from San Jose del Cabo, 

 Lower California. 



