PROF. T. H. HUXLEY ON THE GENTIANS. 107 
A. B. 
Gentiana Gentiana 
Amarella. liniflora. 
campestris. nitida, 
germanica. *inflata. 
tenella. *thyrsoidea. 
*auriculata. . *erassolzema. 
. *nana. *trichostemma. 
*livonica. *scopulosa. 
*acuta. *filamentosa. 
* floribunda. *Ringii. 
* mexicana. 
These are all the types of floral structure which I have met 
with in the Perimelitous series. It will be observed that, look- 
ing at them broadly, they present a general progress, so far as the 
shape of the corolla is concerned, from the stellate form with deeply 
divided lobes in, e. g., G. aurea, to the infundibulate form with 
sharply deflexed lobes in, e. g., G. campestris ; and, so far as 
the difficulty of access to the nectaries is concerned, from the 
Openness to all comers in the first case, to the hiding away at 
the end of horns in Keratanthe, the partial barring of the road 
in Lophanthe, and the more complete obstruction offered by the 
corona in Stephananthe. 
In the series of the Mesomelite the following modifications have 
presented themselves :— 
V. Asteranthe. 
The corolla is rotate, the cup being very short and the lobes 
very long. There are no plice, fimbrie, or other appendages, 
and the expanded flower is widely open. 
I find this structure ouly in the genus Eustoma and in Gen- 
. tiana lutea. I am unable to say anything definite about the 
nectarial surfaces in the former, except that there are none dis- 
coverable on the corolla. In the latter, they are well known to 
form a zone round the base of the ovary. Neither Eustoma nor 
Gentiana lutea are, theoretically speaking, satisfactory represen- 
tatives of the least modified forms of the Mesomelitous series. 
For this purpose a Gentian with a flower like that of G. saxosa, 
but with the nectgries ovarian, is wanted; and I have not been 
able to find any which fulfils this requirement. In Eustoma the 
calyx and the ovary are specialized in the direction of the 
