16 siphonacej:. 



We shall distribute the nine American species into three sections, characterised as 

 follows : — 



Sect. 1. Phyllerpa. Kutz : Fronds piano -compressed, or flat, leaflike, very entire. 



1. Caulerpa prolifera, Lamour.; surculi naked, glabrous ; fronds erect, petiolate, 

 flat, leaflike, nerveless, entire, tongue-shaped, rarely once forked, proliferous from the 

 disc or apex. Lamour. Ess. p. 67. Ag. Sp. Alg. 1, p. 444. Trevis. in Linn. vol. 

 22, p. 129. Phyllerpa prolifera, Kiitz. Sp. Alg. p. 494. Fucus Ophioglossum, Web. 

 and Mohr. Turn. Hist. L 58. (Tab. XXXVIII. B.) 



Hab. Keys of Florida, on submarine sands. Key "West, W. H. H., No. 95. Mr. 

 Ashmead. Soldier's Key, Professor Tuomey, No. 83 in part. (v. v.) 



Surcidi prostrate, throwing out from their under surface branching and fibrilliferous 

 roots, simple or branched, twice as thick as hog's bristle, glabrous, glossy, cylindrical, 

 shrinking, and longitudinally channelled when dry. Fronds stipitate, the stipes 

 filiform, from a quarter-inch to an inch in length, of equal diameter with the surculi, 

 compressed at the apex, and gradually passing into the base of the oblong or 

 obovate, tongue-shaped obtuse lamina. The frond or lamina is flat and leafllike, 

 two to four inches long, from half to three-quarter inch wide, either quite simple 

 or once forked, with a perfectly entire flat margin. Occasionally similar stipitate 

 fronds spring proliferously from any point of the disc or from the base or apex, 

 especially if the latter has been wounded. The substance is membranaceous, somewhat 

 horny and translucent, with a very glossy surface when dry. The colour is a full 

 grass- green, becoming oil-green and variously tinged with yellow in a dried state. It 

 does not adhere to paper in drying. 



This species is rather rare at Key West. My specimens were picked up on the 

 beach, after a southerly gale in the month of February. They closely correspond with 

 specimens from the Mediterranean Sea, where, as well as in the subtropical Atlantic, 

 this plant is not uncommon. C. proUfera has a very difierent habit from the other 

 American species, but is closely related to the Australian C. parvifolia, and to C. anceps 

 from the coral reefs of the Pacific. It appears to be still more closely akin to C. costata, 

 Kiitz, a Mediterranean species unknown to me, and said to differ in having a semi- 

 nerved lamina. 



Plate XXXVIII. B. Fig. 1. Caulerpa prolifera ; the natural size. 



Sect. 2. Ptilerpa. Fronds piano-compressed, inciso-serrate, pinnatifid or pinnate. 



2. Caulerpa Mexicana, Sond. ; surculi naked, glabrous ; fronds erect, subsessile, 

 pinnato-pinnatifid ; rachis (broad), piano-compressed ; pinnae opposite, vertically 



