388 Mr. C C. Babington on the Batrachian llanunculi. 



make a small step towards success, and to place before those 

 who may follow up the study a few additional facts, or an im- 

 proved application of those already known. 



In this group of plants we are not acquainted with any single 

 character which may safely be stated to be always deserving of 

 confidence; but if a combination of several characters is em- 

 ployed, there will rarely be any serious difficulty in identifying 

 the supposed species, even when the structure of some of the 

 parts has undergone change. The look of the plant is generally 

 distinctive of the species ; and the difficulties commence when 

 an attempt is made to draw up technical definitions, or to de- 

 termine the names from " specific characters.'^ Such is found 

 to be the case in most groups of closely allied species inhabiting 

 the " metropolis,^' as it has been called, of extensive and dif- 

 ficult genera. We may call the plants varieties or hybrids, but, 

 until they are proved to be such, we are only avoiding a difficulty, 

 not stating a fact in science. 



Having made these preliminary observations, I will now 

 endeavour to point out the characters upon which we seem to 

 have the most reason for placing dependence in preparing spe- 

 cific characters for the Batrachian Ranunculi, 



It has long been known that the absence of hairs from the 

 receptacle, and of any submersed and filiformly- divided leaves, 

 distinguishes R. hederaceus and its more recently noticed ally, 

 R. ccenosus, from the rest of our native species. It was pointed 

 out by Sibthorp, that the submersed leaves of R. circinatus and 

 R. fluitans had a diff^erent form from those of R. aquatilis, under 

 which latter name he included plants which I have failed in 

 reducing to less than eight species. In these latter plants {i. e. 

 the R. aquatilis of Sibthorp), the submersed leaves are formed 

 of repeatedly-dividing filiform or setaceous parts, which spread 

 in such a manner from their first division, where the leaf trifur- 

 cates, as to take the shape of a greater or less segment of a 

 sphere. These three divisions of the leaf are forked at very 

 short or more distant intervals ; they are fine or rather thick, 

 rigid or flaccid, and accordingly retain their direction when 

 taken out of the water, or collapse so as to resemble a painter's 

 pencil. 



In all the species, the floating or emerged leaves have an out- 

 line which is nearly circular, or only forms part of a circle ; they 

 are divided more or less deeply into lobes, or quite to the top of 

 their petioles into leaflets; in some cases these leaflets have 

 partial petioles of a considerable length, and then the circular 

 outline of the whole leaf is not apparent. When the leaf is 

 formed of lobes or sessile leaflets, the outer margins of the lateral 



