104 
THE CACTACEAE. 
5.5. cm. long; ovary and flower-tube bearing lanceolate acute scales, these without hairs in their 
axils. 
Type locality: Above Balsas in the department of Amazonas, Peru. 
Distribution: Northeastern Peru. 
Through the kindness of F. Vaupel we have been able to study a fragment of this very 
interesting species. It much resembles Matucana haynei. 
12. HAMATOCACTUS gen. nov. 
Globose to short-cylindric, of flabby texture like an Echinocereus, distinctly ribbed, the ribs 
more or less spiraled; areoles circular; spines radial and central, one of them usually hooked; flower- 
bud pointed, covered with imbricating scales; flower-tube narrow, funnelform; limb broad; scales 
on the ovary few, fugacious, small, naked in their axils; fruit small, globular, red, dehiscing by a 
basal pore; seeds black, tuberculate; hilumlarge, basal, circular; embryo straight; cotyledons short 
and thick. 
Echinocactus setispinus Engelmann, the only species here recognized, is the type. 
Although this plant heretofore always passed as an Echinocactus its anomalous charac¬ 
ters have been recognized, such as the texture of the fleshy stem, the fruit, and the seeds; 
Engelmann in his Synopsis of the Cactaceae thus spoke of it: “The compressed ribs, 
setaceous spines, small red berry, and tuberculated seeds easily distinguish it from all its 
allies.” 
The generic name is from hamatus hooked, and cactus, referring to the hooked central 
spine. 
Kigs. i 10 and 111. Fruit and flower of Fig. 112.—Hamatocactus setispinus. 
Hamatocactus setispinus. X0.8. 
1. Hamatocactus setispinus (Engelmann). 
Echinocactus setispinus Engelmann, Bost. Journ. Nat. Hist. 5: 246. 1845. 
Echinocactus muehlenpfordtii Fennel, Allg. Gartenz. 15: 65. 1847. 
Echinocactus hamatus Muhlenpfordt, Allg. Gartenz. 16: 18. 1848. Not Forbes, 1837. 
Echinocactus setispinus hamatus Engelmann, Bost. Journ. Nat. Hist. 6: 201. 1850. 
Echinocactus setispinus setaceus Engelmann, Bost. Journ. Nat. Hist. 6: 201. 1850. 
Echinocactus setispinus cacJietianus Labouret, Monogr. Cact. 203. 1853. 
Echinocactus hamulosus Regel, Ind. Sem. Hort. Petrop. 34. 1856. 
