Mr. Woops on the British Species of Rosa. 215 
the manuscript observations of Professor Swartz, communicated 
by him to Mr. Robertson of Newcastle. 
"The setz which are occasionally met with on the peduncle of 
this tribe of Roses have a very different appearance from those of 
the straight-thorned Roses and of R. Eglanteria and R. micrantha $ 
they are extremely feeble, hardly even stiff enough to support the 
gland by which they are terminated, and frequently passing into : 
mere bairs without any gland: indeed in the former tribe the 
sete seem to indicate an attempt to produce aculei ; and it is 
sometimes difficult to say whether the latter name would not be 
more appropriate : in this they have the appearance of an endea- 
vour to form hairs; and as they gradually diminish in strength and 
in the size of the terminating gland, till at last it entirely disap- 
pears, it is not always easy to decide to which sort of arms they 
belong. Thus, extraordinary as it may seem, we have in this 
genus hairs and prickles passing into one another by steps almost 
insensible. | 
The plant most nearly allied to this is undoubtedly R. canina, 
from which itis to be distinguished by its double serratures: by 
the smooth leaflets without either hairs or glands on the under 
surface, it may be easily known from R. micrantha; and the want 
of hairs will readily distinguish it from R. Borreri and R. cesia ; 
- but as I am always unwilling to rest upon this character alone, - 
when the difference of habit is supported by any other, I will 
observe that the shape of the leaflet, and its being always more 
or less carinate in this species, will be a decided mark of separa- 
tion from the former of these plants ; and the same character, 
though the difference is less distinctly marked, and the pinnæ of 
the calyx leafits, will make it known from the latter. 
| 19. Rosa 
