SIPHONACEiE. 13 



The character seized on by Lamouroux as essential to a definition of the genns, and 

 happily indicated by him in the name Caulerpa (derived from x«i^>.os-, a stem, and 

 epirco, to creep) consists in the prostrate, primary stems or suradi in which the frond 

 origiiiates, 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 

 stipUes 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 m this 

 way may consult a memoir by Count Trevisan in the 22nd vol. of Schlechtendahl's 

 Linna^a 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 Ccmlerpa, 

 a« defined by Lamouroux, includes about fifty species which agree in all essential 

 characters of structure and development. The difierences 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 afibrd stable generic diagnoses. For instance, let us 

 take one of the proposed new genera, Corradoria, which diff-ers from another, Chmmnia, 

 merely in having bifarious instead of multifarious leaves or ramenta. But the feebleness 

 of this character is shown by several species which are imperfectly bifixrious ; so that 

 bifarious and tri- or multifarious ramenta may occasionally be found on one and the 

 same specimen. C. cupressoldes of the North American coast has ramenta sometmies 

 bifarious, sometimes trifarious ; and C falcifoUa 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. lycopodizim, 

 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 prollfera, the type of Kutzing's genus FhijUerpa, we have an example of membranous, 

 expanded, leaflike, simple fronds, perfectly entire at the margin; in C. denticulata anrl 

 C scalpelVformis there are similarly flattened fronds, but deeply pinnatifid ; ni 

 C mexicana the marginal incisions are so deep that the frond becomes pinnate, and 

 thus we are led, by easy transitions, to C tax>folia and C plumaris where the pinnate 

 character is perfectly developed. Again, in C. falcifoUa, Bail. & Harv. there is a 

 passac^e from the species with pinnate fronds to those having filiform ramenta imbncated 

 on all sides ; for, as already mentioned, the ramenta on some of the fronds are strictly 



