98 UNITED STATES AND MEXICAN BOUNDARY. 
16-25 arcte adpressis intertextis superioribus 5-9 setaceis albidis rectis, lateralibus rigidi- 
oribus paulo longioribus infimoque robusto brevi seepe paullo recurvatis; aculeis centralibus 4, 
superioribus radiales excedentibus sursum versis, inferiore brevissimo porrecto robusto; floribus 
parvis in vertice dense lanato congestis purpurascentibus; ovario brevissimo 5-6-squamato; 
sepalis tubi 20 late ovatis cuspidatis albo-marginatis; petalis 20-25 oblongis mucronatis; stylo 
stamina numerosissima vix superante; stigmatibus 7-8 purpureis erectis; bacca globosa sicca 
squamis evanescentibus subnuda basi subpersistente circumscissa; seminibus reniformibus circa 
hilum magnum orbiculare ventrale curvatis tenuiter verruculosis lucidis; albumine parco; em- 
bryone curvato; cotyledonibus foliaceis brevibus. (Tab. XXXIV.) 
Var. 8. DASYACANTHUS: ovatus seu conoideus; aculeis gracilibus longioribus e purpurascente 
cesiis, radialibus 19-25 setaceis pluriserialibus, superioribus 7-9 gracilioribus brevioribus 
albidis fasciculatis, centralibus 4 vix robustioribus, superioribus 3 sursum versis reliquos exce- 
dentibus, inferiore porrecto paullo breviore. (Tab. XXXV, fig. 1-5.) 
On stony ridges from the Limpia to El Paso, Wright, Bigelow, and westward, Parry; also 
towards Chihuahua, Wislizenus; var. 8. common about El Paso: fl. March and April.—Stems 
1-4 inches high, and a little less in diameter; areole 3 or 4 lines apart; upper setaceous 
spines pale,*23-6 lines long, lateral spines 4—7 lines, lowest only 2-4 lines long ; upper 
central spires 5—7 and even 9 lines, lower one 1 or rarely 2 lines long; in young plants the 
13-15 radiating spines are more equal in length, and several or all of the central spines are 
wanting. Flowers about an inch long and wide; sepals dark purple with paler margins; petals 
similar, outer ones deeper, inner ones gradually lighter colored ; stamens more than 650, half 
as long as petals. Fruit about 4 lines in diameter, tipped by the withered flower, usually with 
a few dry scales, with or without some wool in their axils; the base usually persistent for some 
time, while the upper part comes off, separating more or less regularly, Seeds nearly or quite 
one line long, with a very large hilum. 
Var. #. has the flowers and fruit of var. a, but is a larger plant with much longer and slenderer 
spines, lower central spine almost as long as the others. Spines in var. a. appressed so that the 
plant resembles somewhat, and has been confounded with, Cereus viridiflorus. In var. 8. the spines 
are loosely patulous, forming a tuft on the top; the whole plant is very similar to Mam. dasy- 
acantha ; the entire similarity of flower and fruit, and the intermediate forms of the spines, leave 
no doubt of both plants belonging together, though their external appearance is so very dis- 
similar. 
Ill. CEREUS, Haw. 
Subgen. 1. Ecurnocerzus, E.* 
1. C. viriprrLorus, E. in Wisl. Rep. 8. cynnpricus: ovatus seu plerumque cylindricus, sub- 
simplex; costis sub-13 acutis fere interruptis; areolis confertis ovatis seu ovato-lanceolatis, 
* This subgenus, which was indicated by me in the Appendix to Wislizenns’ Report asa genus distinct from Cereus, and 
reduced to a section of that genus, is well charac- 
ve mentioned. The numerous species since discov- 
€ of any other Cactacee examined by me, They are 
rather small, never so much as One line (between 0.4 and 0.9 line) in length, obliquely obovate or subglobose, padi or Af 
pressed, and with a circular or oblong basilar or sub-basilar hilum; testa black, hard, and brittle, always tuberculated ; its 
tubercles large or small, equal or unequal, distinct or more or less confluent, and then leaving : 
