119 
Specimens examined: TEXAS ( Wright 18, 19, 20, 23, 24, 29, 30, 31, 32, 
535, of 1849 and 1852; Bigelow of 1852; Engelmann, with no number or 
date; Evans of 1891): CHIHUAHUA (Pringle 250, 251 in part, and 258 
of 1885): COAHUILA (Palmer of 1880): also specimens from Coll. Salm- 
Dyck in 1857; also growing in Mo. Bot. Gard. 1893 (specimens sent by 
G. G. Briggs in 1892 from El Paso, Texas. 
The identification of Engelmann’s tuberculosa with Scheer’s strobiliformis was made 
by Dr. Engelmann himself upon an examination of Scheer’s type. The use of the 
specific name ‘uberculosa is necessitated by the law of homonyms, as strobiliformis 
had been used twice already before it was taken up by Scheer. M. strobiliformis 
Muhlenpf. is C. scolymoides sulcatus; and M, strobiliformis Englem. is C. conoideus. 
57. Cactus viviparus Nutt. in Fraser’s Cat. (1813). 
Mamillaria vivipara Haw. Syn. Succ, Suppl. 72 (1819). 
Low and depressed-globose, usually proliferous and cespitose (form. 
ing large masses), but sometimes simple: tubercles terete and loose, 
lightly grooved: radial spines 12 to 20, stiffand white, often dark-tipped, 
6 to 8 mm. long; central spines usually 4 (sometimes less, often more, 
even as many as 8), brownish, 8 to 12 mm. long, 3 spreading upwards, 
the lowest stouter and shorter and deflexed: flowers about 3.5 em. long 
(large for the size of the plant) and even broader when expanded, 
bright purple: stigmas pointed with a short mucro: fruit oval, pale 
green, juicy, 12 to 13mm. long: seeds yellowish-brown, obliquely obo- 
vate and curved about the small hilum, 1.4 to 1.6 mm. long). (Ill. Cact. 
Mex. Bound. t. 74. fig. 3, seeds) —Type unknown. 
_ On the northwestern plains, from the boundary provinces of British 
America (western Manitoba, Assiniboia and Alberta), and throughout 
the Upper Missouri region, southward through western Nebraska to 
western Kansas and to the eastern foothills of central Colorado. It is 
also mentioned by Howell (Cat. of Oregon, Washington and Idaho 
plants), as occurring beyond the Rocky Mountain divide in Idaho and 
Washington, which is probable, but no specimens have been seen. 
Specimens examined: MONTANA (Hayden, nos. 1854, 1855; Vernon 
Bailey of 1890, near Bridger): COLORADO (Hayden of 1869): NEBRASKA 
(Rydberg 1379 of 1893, Thomas Co.): also specimens cultivated in 
St. Louis in 1869; also growing in Mo. Bot. Gard. 1893. 
It seems best to keep this northwestern form specifically separate from that large 
assemblage of southern forms that have been commonly referred to it. The forms 
referred to this species from western Kansas (Smyth’s check list) have not been 
examined, and they may represent intermediate forms, inclining to simple habit and 
ovate form, asin the Colorado forms. The southern type (C. radiosus) is distin- 
guished from C. viviparus not only by its very different range, but also by its ovate 
to cylindrical form, simple habit, more numerous (12 to 40) and longer (6 to 22 mm.) 
radial spines, usually more numerous (3 to 14) central spines in which the upper are 
more robust than the lower, porrect lower central, obtuse stigmas, and brown 
obovate straight seeds. 
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