202 THE JOURNAL OF BOTANY 



usciila) ; (3) a scrap which may be R. omissa Deseg. ; (4) another 

 scrap which is quite doubtful. These points, however, have all 

 been taken up by later continental students, and would appear to 

 offer the best available means of a more elaborate classification. 



In the following paper the classification of the members of the 

 group has been based (1) on the direction, persistence, and curva- 

 ture of the fruiting sepals ; (2) on the curvature of the mature 

 thorns; and (3) on the clothing of the leaves in respect of glands. 

 The differences implied in (1) and (2) appear to be structural, and 

 to afford reliable grounds of specific distinctions. It is doubtful 

 how far this is the case with (3) ; but differences of gland develop- 

 ment imply, in the opinion of the writer, something more funda- 

 mental than mere changes of soil, exposure, &c. "While therefore 

 it has not been thought allowable to unite in a single variety 

 glandular and eglandular forms, they can permissibly be grouped 

 together as varieties under a single species. 



Moreover, the leaf-glands are so easily observed at all stages of 

 the plant, that a systematist would not willingly abandon their 

 help. No notice has been taken of the shape or curvature of the 

 stipules, to which Crepin draws attention ; these being points 

 which need much study from the living bushes, and on the 

 diagnostic value of which there is great difference of opinion. In 

 this paper the shape of the leaflets is taken exclusively from the 

 terminal one. 



A few words may be allowed upon the selection and preparation 

 of specimens. No rose specimen can be considered satisfactory, 

 especially in this group, which does not exhibit the larger thorns 

 of the mature branches, the shape of which is of much importance 

 in the discrimination of the forms ; also the fruit in a stage at least 

 approaching to ripeness, so that the character of the fruiting sepals 

 can be determined. Flowering-sprays and pieces from the vigorous 

 shoots of the year are also desirable, but are not of primary impor- 

 tance ; the shape of the thorns especially should not be judged of 

 entirely from those of the first-year shoot. The character and 

 prominence of the disk as well as colour of the petals should be the 

 subject of a written note made at the time of gathering ; and the 

 leaves of all specimens should be so dried as to exhibit both the 

 upper and under surface at once on the same piece. 



It has been thought more in accordance with nature to treat the 

 whole number of forms here dealt with as a single group, the 

 members of which, exclusive of varieties, may legitimately be 

 assumed to be of equal value and termed species ; moreover, most 

 of them were originally described as species. The arrangement 

 into two species, mollis and tomentosa, the latter with numerous 

 varieties, melts away when the group is studied ; although, as 

 divisional names, these still remain advantageous. 



The thanks of the writer are due to many botanical friends who 

 have placed their collections at his disposal for study ; to Mr. James 

 Britten for many valuable critical hints, and to Mr. E. G. Baker 

 for assistance without which this paper could not have been 

 undertaken. 



