GoRHAM, on tilis Umbellifera. 25 



in certain of tlie insect tribe, which are prone to disturb our 

 peace, and especially to induce a strong presentiment of a 

 nocturnal vioil. 



By way of conclusion I would offer the following brief re- 

 capitulation : 



1. That the distribution of the veins in Umbelliferse is very 

 variable in different sjjecies, but constant and highly charac- 

 teristic in each species. 



2. That many of the leaves of this order have a venation like 

 that in other leaves, and may be classified with them ; but 

 that a considerable number of them, on the other hand, have 

 a kind of venation peculiar to themselves, which does not 

 find a place under any of the divisions that have heretofore 

 existed. 



3. That this peculiarity consists in the existence of a vein 

 at the very edge of the leaf itself, and which, more or less, 

 entirely fringes its whole margin. 



4. That this marginal vein is to be found certainly in one 

 half, if not more, of the species belonging to the Umbelliferae, 

 and hence that it may be said to constitute a form of venation 

 peculiar to this order, and to give a character to it which does 

 not belong to other orders of plants. 



5. That when a leaflet is placed between two pieces of glass, 

 and examined with a Ioav power of 12 diameters, the vein 

 becomes distinctly visible. 



6. But that it is also visible, even to the naked eye, in 

 certain of the species — Eryngium maritimum, E. campestre, 

 Silaus pratensis, &c. 



7. And, finally, that it is possible that a more attentive 

 study of the venation of leaves in the manner recommended 

 in this paper might prove of considerable assistance in the 

 classification of plants. 



For a full description of the veins in ferns I would beg to 

 refer to the elegant volume, ' Ferns, British and Foreign,' 

 by Mr. John Smith ; but I am not aware that an analogous 

 description of the venation in any one single order of flower- 

 ing plants has ever been attempted. 



I noAv beg to offer my thanks, first to the worthy Honorary 

 Secretary of the Royal Microscopical Society, for the kind 

 and flattering manner in which he has received and disposed 

 of my paper ; and, secondly, to the President and Fellows 

 themselves, for the honour they have conferred upon me in 

 allowing me to read and discuss its merits before them on the 

 present occasion. 



