SIPHQNACEiE. 
13 
The character seized on by Lamouroux as essential to a definition of the genus, and 
happily indicated by him in the name Caulerpa (derived from av\os , a stem, and 
ipirco, to creep) consists in the prostrate, primary stems or surculi in which the frond 
originates, and which are furnished at intervals throughout their length with branching 
and fibrous roots that penetrate deeply into the sand in which the plant vegetates, or 
attach themselves firmly to the rock in such species as grow on rocks and corals. 
These roots are fibrous prolongations of the under surface of the prostrate stems, and 
are probably, notwithstanding their great development, chiefly useful for fixing the 
plant in its position. From the upper side of the surculi rise erect branches or secondary 
fronds, which are very various in form, and are either sessile or supported on stalks or 
stipites .of greater or less length. Some recent writers on these plants have proposed to 
divide the genus into several, assigning to them characters taken from the form and 
ramification of the branches ; and those who wish to know what can be done in this 
way may consult a memoir by Count Trevisan in the 22nd vol. of Schlechtendahl’s 
Linneea, where subdivision is pushed to an extreme. I have not adopted these views 
of arrangement, being unwilling to break up what appears a natural assemblage, and 
thus needlessly to multiply generic names. By employing artificial characters it is very 
easy to split up any genus of several species, but unless the number of species included 
in a genus be inconveniently large, it seems undesirable to do so. The genus Caulerpa , 
as defined by Lamouroux, includes about fifty species which agree in all essential 
characters of structure and development. The differences among them are obviously 
of a very minor character, and though proper enough for the definition of sections, are 
we think of too trivial a nature to afford stable generic diagnoses. For instance, let us 
take one of the proposed new genera, Corradoria , which differs from another, Chauvinia, 
merely in having bifarious instead of multifarious leaves or ramenta. But the feebleness 
of this character is shown by several species which are imperfectly bifarious ; so that 
bifarious and tri- or multifarious ramenta may occasionally be found on one and the 
same specimen. C. cupressoides of the North American coast has ramenta sometimes 
bifarious, sometimes trifarious ; and C. falcifolia of the tropical Pacific, which is nor- 
mally bifarious, is frequently quadrifarious on part of the same individual. 
In all the North American species the ramenta are confined to the upright branches 
or secondary fronds, and the surculi are smooth and glossy except in C. lycopodium , 
where both the surculus and the stalks of the fronds are densely clothed with branching, 
woolly hairs. In several Australian and some Pacific species the surculi are equally 
ramentiferous with the fronds, though the ramenta they bear are often of a different 
shape. The forms and ramifications of the upright fronds are much varied. In our 
C. prolifer a, the type of Kutzing’s genus Phyllerpa , we have an example of membranous, 
expanded, leaflike, simple fronds, perfectly entire at the margin ; in C. denticulata and 
C. scalp ellif or mis there are similarly flattened fronds, but deeply pinnatifid ; in 
C. mexicana the marginal incisions are so deep that the frond becomes pinnate, and 
thus we are led, by easy transitions, to C. taxifolia and C. plumaris where the pinnate 
character is perfectly developed. Again, in C. falcifolia,, Bail. & Harv. there is a 
passage from the species with pinnate fronds to those having filiform ramenta imbricated 
on all sides ; for, as already mentioned, the ramenta on some of the fronds are strictly 
