OF ARTS AND SCIENCES : MAY 13. 1873. 651 



rather narrower and longer squamella? ; but otherwise I see no dif- 

 ference. 



Ach^togkron Gray, PL Fendl. p. 72. This is overlooked in 

 the Genera Plantarum; else it would probably have been referred to 

 Erigeron as a sort of Phalacroloma without bristles either in disk 

 or ray. But technically, and perhaps with sufficient reason every 

 way, it should hold its rank as a genus in the Bellidece, just before 

 Myriactis. 



Baccharis. The receptacle is conical in B. Douglasii DC. 



Evax. The paleae of the receptacle vary from strongly carinate- 

 cyrabiform in some species (as in E. Heldrichii, in which they are 

 wholly pointless) to barely concave in others : in E. perpusilla there 

 are subtending and partly enclosing paleae for each sterile flower. Our 

 Californian Hesperevax may very well remain in the genus ; but it 

 constitutes a marked subgenus, not only on account of the firm and at 

 length rigid,, comparatively persistent involucral scales and paleaa which 

 are barely concave, but also on account of the receptacle. This is not 

 correctly represented on the plate in Bot. Whippl. Exped. The body 

 of it, on which most of the fertile flowers are borne, is rather convex 

 than conical* beset with villous hairs, which are fully as long as the 

 achenia, and abruptly produced at the centre into a narrow column, 

 which bears very i'aw or hardly any pistillate flowers and paleae except 

 near its base, while its summit bears a whorl of three to five, broadly 

 ovate or obovate, blunt or sometimes mucronate, flat paleae, of nearly 

 herbaceous texture, more or less woolly inside, forming an involucre to 

 the small cluster of hermaphrodite-sterile flowers, rigid and radiately 

 spreading with age, at length deciduous. The achenia, moreover, are 

 smooth (not papillose or glandular), clavate-obovate and decidedly 

 obcompressed. The transverse brownish line above their base is 

 marked in the coat of the seed. The diversity in the villosity of the 

 receptacle, and the length and thickness of its elevated portion (being 

 very slender, even filiform, and a line high, in no. 415 of Kellogg and 

 Harford's collection), appeared to indicate more than one species, but I 

 cannot make them out. 



Micropus. The generic character in the Genera Plantarum by an 

 oversight requires the fertile flowers to form only a single series. I 

 should hardly change that ; for the genus clearly appears to me to hold 

 only the first two sections, and to rest on two good and peculiar charac- 

 ters : 1, the paleae, which so completely and strictly enclose the achenia, 



