116 ERYTHEA. 



Straight central spines, but in the numerous specimens brought from 

 San Benito Island ^ (it has been found nowhere else), many have 

 the lower central hooked and darker, as in the type of dioica. 

 Both the type and the variety are nearly diogcious, many plants 

 male, with imperfect, less-divided style-branches, which rarely bear 

 fruit, and the few which occasionally appear very slender and few- 

 seeded ; many female, with entirely abortive anthers and very small 

 flowers, which usually produce a dense row of thick oval or clavate, 

 coral berries; others hermaphrodite or imperfectly dioecious in all 

 degrees. 



It is probable., that many species of Mamillaria have the same 

 peculiarity. I have observed plants of other species growing in our 

 gardei}, which were completely unisexual. 



Mamillaria (Lactescentes) Brandegel Engelm. in Coult. 

 Cactus Brandegei Coult. 1. c. 96. 



Mamillaria (Lactescentes) Gabbii. Engelm. in Coult. 

 Cactus Gabbii Coult. 1. c. 109. 



These two plant;g are closely related and may belong to a single 

 species. Mr. C. R. Orcutt has collected not far from San Quentiu 

 a form which is intermediate. The species of this section are un- 

 usually variable in their spines and the peninsular forms may be 

 variations of species found in Mexico proper. 



Mamillaria (Cochemiea) Halei. Brandg. Proc. Cal. Acad, 

 ser 2, ii 161. Stems clustered 3-5 dm. high; tubercles rather 

 crowded, short conical from a broad base, woolly but not setose in 

 the axils; spines 15-25, sub 3-seriate, all straight, centrals 6-9, the 

 lower one 3-4 cm. long, porrect or deflexed, twice as long as, and 

 much stouter than the others, radial spines shorter than the centrals, 

 variable in number and arrangement; flowers 4-5 cm. long. 



Collected so far only ou Magdalena and Santa Margarita Islands. 

 Mamillaria (Cochemiea) Pondii Greene, Pitt., i, 268. Stems 1-4 

 dm. hio-h, branching at and along the whole length of the older reclin- 

 ing ones, tubercles short, conical, not crowded, with woolly and con- 

 spicuously setose axils; spines 25-35 in about 3 series, whitish, light 



* Confined so far as known to this island, unless Palmer's No. 901 

 from Guadalupe Island, Contr. Nat. Mus. i, 24, may belong to this 

 variety. 



