438 PROCEEDINGS OF THE AMERICAN ACADEMY. 



II. REVISIONS OF ALOMIA, AGERATUM, AND OXYLOBUS. 

 By B. L. Robinson. 



The following treatment has been based chiefly upon an intensive 

 study of the pertinent material in the Gray Herbarium, but much aid 

 has been derived from a series of photographs, taken at various P^uro- 

 pean herbaria in 1905 and 1910, representing the types of nearly all 

 the recognized species of Alomia and Agenitum not originally described 

 from the Gray Herbarium. There has been no opportunity to test 

 the keys and descriptions by a re-examination of the extensive material 

 in foreign collections, but through the kindness of Messrs. Coville 

 and Maxon the writer has been permitted to borrow and stud\' the 

 representation of Alomia and Agcration from the National Museum at 

 Washington, a considerable privilege for which he would express great- 

 ful appreciation. The writer is also much indebted to Mr. John 

 Donnell Smith for the loan of Agendum and Alomia from his rich 

 personal herbarium, anrl to IVIr. A. B. Rendle of the British Museum 

 of Natural History for the critical comparison estal)lishing l)e\ond 

 doubt the identit}' of Agerafuin Ilousionianuni Mill. Miss M. A. Day 

 and IMiss E. M. Vincent of the Gray Herbarium staff have given 

 bibliographical aid. 



It may l)e said in a general way that the species of these genera do 

 not teufl to serious intergradation, except in the case of Agcratum 

 conyzoidcs L. and .1. lafifolium Cav. (not Hemsl.), where separation 

 though easily made seems pretty artificial, and on the other hand the 

 several species which are closely allied to the highly variable .1. 

 coripnhosum Zuccag. and are distinguished chiefly by such characters 

 as leaf-contour, pubescence, etc. 



It must be frankly admitted that the treatment of the South 

 American species is ^•ery sketcliy, being deri\ed from wholly inade- 

 quate nuiterial. It is highlx' })robable that further exploration of north- 

 ern South America and of Brazil will bring to light many further 

 species, and perhaps consitlerabl,>' modify our present views as to the 

 distinctness of those already known. 



1. Revision of the Genus Alomia. 



The tropical American genus Alomia is a convenient rather than a 

 convincingly- natural group of species. Depending for its separation 



