256 
JOURNAL OF THE PLYMOUTH INSTITUTION. 
posed to question its being a native of England ; but it is most 
certainly indigenous in many places in Devon. A most local plant 
of the Umbelliferce is Trinia vulgaris, D.C., found in Devon at 
Berry Head, and elsewhere in the United Kingdom only on St. 
Vincent's Kocks, Gloucester • and at Uphill and Worle Hill in 
Somerset. In this we witness a dioecious and probably biennial 
species maintaining its existence at certain circumscribed spots with 
a persistence like that of the monoecious and perennial Eryngium 
campestre, L., at its station in our immediate neighbourhood. I 
speak of the Trinia as probably biennial, as whilst the respective 
authors of the Student's Flora and English Botany, ed. 3, state it 
to be so, those of the Handbook of the British Flora and of the 
Manual of British Botany call it perennial. Here we find authors 
of the highest authority divided in opinion on a point that could 
soon be settled by original observation and experiment. It is a 
species of southern and western Europe, and in our moist climate 
occurs only in dry warm spots. In the character of the situation it 
affects it contrasts most remarkably with Carum verticillatum, 
Koch., a species of damp marshes and bogs. In the neighbourhood 
of Plymouth this is only known to occur in one place situated in 
the parish of Plympton St. Mary, and not elsewhere in South 
Devon, though in some parts of North Devon and a neighbouring 
portion of East Cornwall it is in plenty, as is likewise the case in 
some parts of Wales and Ireland, and in Western Scotland. On 
the Continent it preserves a western distribution also, occurring 
from the Spanish Peninsula to Belgium. Probably the dry cold of 
central Europe and the more parching heat of its summers would 
not suit this Carum; but we cannot suppose that the climatal 
conditions of some places where it is not to be seen, West Corn- 
wall for instance, would be unsuited to it. I have no doubt that 
something beyond climate, soil, and species competition must have 
worked to bring about the present remarkable and seemingly 
arbitrary ranges of many of our Umbelliferce. The age of a 
particular geological formation has possibly, in certain cases, some- 
thing to do with the presence of a species on it ; more perhaps than 
the chemical elements of its rocks, or even their lithological com- 
position. I will give here in a translation some admirable remarks 
by De Candolle, suggested by facts seen at present in species dis- 
tribution. " Certain species," says he, "grow in one region, and 
are absent from another, where they could perfectly live under 
