GENERAL SYSTEMATIC BACTERIOLOGY 133 



higher or lower rank than before, the change is equivalent to the creation of a new 

 group and the author who has affected the change is the one to be quoted. The 

 original author can be cited only in parenthesis. 



Examples : Cheiranthus tristis L. when moved into the genus Matthiola becomes 

 Matthiola tristis R. Br., or Matthiola tristis (L.) R. Br. — Medicago polymorpha L. 

 var. orbicularis L. when raised to the rank of a species becomes Medicago orbicu- 

 laris Ail. or Medicago orbicularis (L.) All. 



Comment. The corresponding zoological rule requires that the origi- 

 nal author shall be cited in parenthesis instead of leaving it optional as 

 in the above article. 



Recommendation. XXV. Author's names put after names of plants are abbre- 

 viated, unless they are very short. 



Section 6. On names that are to be retained when a group is divided, 

 remodelled, transferred, or moved from one rank to another, or when two 

 groups of the same rani: are united, or when they concern groups possess- 

 ing a pleomorphic cycle 



Article 44. A change of characters, or a revision which involves the exclusion 

 of certain elements of a group or the addition of new elements, does not warrant 

 a change in the name or names of a group, except in cases provided for in article 51. 



Examples : The genus Myosotis as revised by R. Brown differs from the original 

 genus of Linnaeus, but the name has not been changed, nor is any change allow- 

 able. Various authors have united with Centaurea Jacea L. one or two species 

 which Linnaeus had kept distinct; the group thus constituted must be called 

 Centaurea Jacea L. (sensu ampl.) or Centaurea Jacea L. (em. Visiani, em. Godron, 

 etc.) ; the creation of a new name such as Centaurea vulgaris Godr. is superfluous. 



Article 45. When a genus is divided into two or more genera, the name must 

 be kept and given to one of the principal divisions. If the genus contains a section 

 or some other division which, judging by its name or its species, is the type or the 

 origin of the group, the name is reserved for that part of it. If there is no such 

 section or subdivision, but one of the parts detached contains a great many more 

 species than the others, the name is reserved for that part of it. 



Examples: The genus Helianthemum contained, according to Dunal (in DC. 

 Prodr. I. 266-284), 412 well-known species distributed in nine sections; several 

 of these sections have since been raised to generic rank (Fumana Spach, Tuber- 

 aria Spach) but the name Helianthemum has been kept for the divisions 

 grouped round the section Euhelianthemum. The genus Convolvulus L. em. 

 Jacq. was divided into two by Robert Brown in 1810 {Prodr. fl. Nov. Holl., 

 p. 482-484), who gave the name Calystegia to one of the genera which at the 

 time contained only four species, and reserved the name Cojivolvulus for the 

 other genus which contained a much larger number of species. In the same 

 way Salisbury (in Trans. Linn. Soc. VI, 317, 1802) in separating Erica vul- 

 garis L. from the genus Erica, under the name Calluna, kept the name Erica 

 for the large number of species left. 



